Srila Prabhupada explains below, that all jiva-souls are eternal persons whose original appearance is a Spiritual bodily form like Krsnas.

The jiva-soul's (marginal living entities) original bodily form is having the same bodily features as Krsna, which is- 

sat, 

cit, 

ananda, 

vigraha. 

Which means- 

eternity, 

knowledge,

bliss,

form.

The jiva-souls (marginal living entities) are eternal persons as a Spiritual bodily form like Krsnas.

The full potential and original feature of all marginal living entities (jiva-souls) is a two arm form like Krsna's Form.

Devotee – "Is the original body of the spirit soul a human form?"

Srila Prabhupada – "Yes, human form. God is also human form. "Man is made after the shape of God." I think there is in the Bible. Is it not? So God is also like human form. Here you see Krsna, two hands, two legs."

Hari-sauri – "How do we understand, then, that there are peacocks and flowers and trees in the spiritual world? Are these not eternal forms?"

Srila Prabhupada – "[describing material form first]: Yes, they are more covered. Just like if you cover your body with blanket, the hands and legs are invisible. But you are not the blanket. So the trees and plants, they are more covered. They are not in full manifestation. The human form is the full manifestation of the soul."

Hari-sauri - "They are covered in the spiritual world?"

Srila Prabhupada - "Not in the spiritual world. There that is voluntary. Some devotee wants to serve Krsna as flower; they become flower there. If I want to be a flower I shall lie down at the lotus feet of Krsna, he becomes flower, voluntarily, and he can change his, from flower to human body. That is spiritual life. There is no restriction. If some devotee wants to serve Krsna as cow, he serves Krsna as cow, as calf, as flower, as plant, as water, as ground, field, or as father, as mother, as friend, as beloved, anything. It is inconceivable, yet a fact." (SB Canto 6.1.1-4 - Melb, May 20, 1975)

Also it is from Goloka-Vrindavana that some jiva-souls choose to enter the Vaikuntha Planets and appear there in a blue four armed form similar to Lord Visnu.

The appearance of eternal youth only exists on the Vaikuntha Planets, where as in Goloka Vrindavana one does not have a body that is blue like Krsnas, there it is different with more variety of bodily forms.

It is one's "rasa" or voluntarily desired association with Krsna that is eternal, what ever body or form that maybe.

But this can obviously change over an infinity, like eventually being Krsna's uncle, parents, the old shop owner on the corner, a blade of grass, cloud, snow flake, cow or tree etc.

Bodily appearance there is according to pastime, every male human form does not look the same in Goloka-Vrindavana like they do on the Vaikuntha planets.

Many quotes about the jiva-soul's features explains their journey as a bodiless spark of consciousness entering the material world, or merging as an individual unit into the impersonal Brahmajyoti, or as a spark within Krsna's bodily effulgence, the brahmajyoti.

But this "bodiless inactive spark" is already a fallen impersonal condition of the jiva-soul and does not describe the jiva-soul's original position and full potential as an eternal PERSON,  AS a two armed bodily form.

There in the Brahman effulgence or dormant Brahmajyoti, the individual jiva-souls are described as an "inactive spark of consciousness" who enters the impersonal Brahmajyoti after becoming frustrated with the material creation's terrible cycle of repeated birth and death, experienced in temporary material bodily vessels in the material creation.

Only when Prabhupada talks about the impersonal Brahmajyoti does he call the jiva-soul a spark, and then clearly adds that appearing as an impersonal spark in Krsna's effulgence, is a fallen condition that the jiva-souls fall down too.

This is because originally, the jiva-souls were all PERSONS in the pastimes of Krsna as individual spiritual bodily forms (vigraha).

Srila Prabhupada also explains this in a more simple way, that the jiva-souls have fallen from the personal pastimes of Krsna to the material creation, or further to the impersonal Brahmajyoti.

Ultimately, Prabhupada explains below, that all jiva-souls are eternal persons as their original Spiritual bodily form.

Srila Prabhupada - "In the broader sense everyone comes from Krsna Loka. When one forgets Krsna he is conditioned, when one remembers Krsna he is liberated." (Letter to Mukunda, June 10, 1969)

Srila Prabhupada - "We cannot say therefore that we are not with Krsna. As soon as we try to become Lord, immediately Maya covers us. Formerly we were with Krsna in His lila or sport. But this covering of Maya may be of very, very, very, very long duration; therefore many creations are coming and going." (Letter to Madhudvisa Swami June 1972 Australia)

Srila Prabhupada - "So to go to Krsna means you will have to acquire your original, spiritual body. The spiritual body is already there, but we are now covered by this material body." (Germany, June 22, 1974)

Srila Prabhupada - "We have also come down from Vaikuntha some millions and millions of years ago." (Lecture, BG Aug 6, 1973)

Srila Prabhupada - "These spirit souls and all spirit souls are coming from Vaikuntha." (Letter to Jagadisa das, 1970)

Srila Prabhupada – "Regarding your several questions: Where are the spirit souls coming from? These spirit souls and all spirit souls are coming from Vaikuntha." (Letter to Jagadisa 7/9/1970)

Acyutananda - "So what made the jiva-soul take birth in the first place in the material world?"

Srila Prabhupada - "In the first place?"

Acyutananda - "What is the first birth? What is the cause of the first birth."

Srila Prabhupada - "Yes, that is stated in the Prema-vivarta:

krsna-bahirmukha hana bhoga vancha kare nikata-stha maya tare japatiya dhare

We are eternal servant of Krsna. As soon as we want to become master, that is the beginning of our first birth in the material world. We have got independence. Krsna says, mamaivamso jiva bhutah—we are part and parcel of Krsna—so Krsna has got full independence, but we are minute; therefore we have got minute independence. 

Our business is to serve Krsna, but as soon as we give up this idea, we want to become master. That is the beginning of our material birth." (Lecture, SB Canto 5.5.2-Hyderabad, April 11, 1975)

Acyutananda - "But in the Bhagavad Gita As It it says, "Once coming to the material world , he never returns."

Srila Prabhupada - "But if he likes, he can return."

Acyutananda - "He can return?''

Srila Prabhupada - "That independence has to be accepted, little independence. We can misuse that. Krsna-bahirmukha hana bhoga vancha kare. That misuse is the cause of our falldown."(Morning Walk, Feb 19, 1976, Mayapur)

The marginal living entities (jiva-souls) are not called tatastha-sakti in Vaikuntha or Goloka Vrindavana, it is a name describing the fallen conditioned state of the jiva-souls in the material creation and the impersonal Brahmajyoti. 

The jiva-souls did not originate from tatastha-sakti, they came from Vaikuntha and also originally from Goloka-Vrindavana. 

Srila Prabhupada - "So this "material world" is the taṭastha (conditioned characteristics), and the "Spiritual Worlds" are the "Personal" (characteristics). So our effort is to get out of this taṭastha (conditioned characteristics) and enter the permanent characteristics (Vaikuntha and Goloka-Vrindavana). That is called spiritual elevation." (New York City, December 28, 1966)

Revatīnandana - "Srila Prabhupāda you very clearly explained to me once in a letter that if the jiva-soul then goes into the brahmajyoti, he is considered still fallen. Still fallen. Does that means the whole brahmajyoti is composed of fallen souls? You see my question? If I go there, I'm a jīva-soul, and I go to the brahmajyoti I'm still fallen."

Srila Prabhupāda - "Yes."

Revatīnandana - "That means all jīva-souls there are also fallen souls?"

Srila Prabhupāda - "Yes, existence in the impersonal brahman is also within the category of non-Krsna consciousness. Those who are in the brahman effulgence are also in the fallen condition, so there is no question of falling down from a fallen condition." (Letter to: Revatinandana, Los Angeles 13 June, 1970)

Srila Prabhupada - "When fall takes place, it means falling down from the non-fallen condition. The non-fallen condition is Krsna consciousness." (Letter to: Revatinandana, Los Angeles 13 June, 1970)

As explained above, in the jiva-soul's original position, they have the same bodily features as Krsna, 

1 - sat,

2 - cit,

3 - ananda,

4 - vigraha,

Which means a spiritual bodily vessel that is -

1 - eternity 

2 - knowledge, 

3 - blissful.

4 - And all held together by individual bodily form.

Srila Prabhupada - "Actually the spiritual body means eternal life of bliss and knowledge. This material body which we are possessing now, is neither eternal, nor blissful, nor full of knowledge. 

The spiritual body is full of knowledge, just opposite. So we can get that body next life, we have to cultivate how to get that type of body. Therefore the best intelligent person will try to get next body full of blissfulness, knowledge, and eternity." (Lecture BG 2.14, Mexico, Feb 14, 1975)

Srila Prabhupada - "The relationship with Krsna is never lost, it is simply forgotten by the influence of maya, so it maybe regained or revived by the process of hearing the Holy Name of Krsna and then the devotee engages himself in the service of the Lord which is his original or constitutional position. The relationship of the living entity with Krsna is eternal as both Krsna and the living entity are eternal; the process is one of revival only, nothing new." (Letter to Jagadisa 02/27/1970)

Devotee - "Srila Prabhupada why did Krsna give us free will if He knew we could fall down in the material world?"

Srila Prabhupada - "If you have no free will, then you are a stone. The stone has no free will. You want to be stone? Then you must have free will. But don't misuse your free will. But don't try to become stone either. That is not life." (Aug 5, 1976, New Mayapur France) 

 Srila Prabhupada - "Can we predict that returning back home back to Godhead will be permanent? Can we predict that?

Syamasundara - "Can we predict that returning back home back to Godhead will be permanent? Can we predict that? Just like many prisoners leave the prison, however, some do come back?"

Srila Prabhupada - "No, there is no permanent effect because we have got little independence. There is nothing permanent because you can misuse your independence at any time."

Syamasundara - "And some come back?"

Srila Prabhupada - "Yes, otherwise there is no meaning of independence. Independence means you can do this, you can do that. "All right. Whatever you like."

Devotee - "Then he is so many times falling down, again and again, so will he eventually permanently come back?"

Srila Prabhupada - "He has got independence, therefore there is always the possibility he can misuse his independence, he can fall down. That's why when a man is released from the prison house, that does not mean permanently because he can come back again, the general law is not to come back, but if he likes, he can come back, otherwise what is the meaning of independence? Just like one becomes free from the prison house, naturally he should not go there again." (Discussions with Syamasundara > Henri Bergson)

Srila Prabhupada - ''As soon as we try, "Oh, this material world is very nice," "Yes," Kṛṣṇa says, "yes, you can go." Otherwise what is the meaning of free will? Every living entity has got a little free will. And Kṛṣṇa is so kind, He gives him opportunity, "All right, you enjoy like this." It is free will." (Morning Walk Cheviot Hills May 13, 1973, Los Angeles)..^*^..