That's an interesting take on those verses. How do you know it isn't the result of sin that causes this? Do you find other scripture to support this?
It goes back to Adam being mortal. No verse anywhere says he was created immortal and sinned and became mortal. I believe this shows Adam was mortal:
1Co 15:44 It is sown a natural body; it is raised a spiritual body. There is a natural body, and there is a spiritual body.
1Co 15:45 And so it is written, The first man Adam was made a living soul; the last Adam was made a quickening spirit.
1Co 15:46
Howbeit that was not first which is spiritual, but that which is natural; and afterward that which is spiritual.
Adam was in the natural body which is mortal NOT the spiritual body which is immortal.
A natural body is intended to die and be raised a spiritual body. Paul knew Adam was not created immortal because he says the first man was made "natural" which was a natural body as opposed to the "spiritual body" which is immortal.
1Co 15:39 All flesh is not the same flesh: but there is one kind of flesh of men, another flesh of beasts, another of fishes, and another of birds.
1Co 15:40 There are also celestial bodies, and bodies terrestrial: but the glory of the celestial is one, and the glory of the terrestrial is another.
1Co 15:43 It is sown in dishonour; it is raised in glory: it is sown in weakness; it is raised in power:
1Co 15:44 It is sown a natural body; it is raised a spiritual body. There is a natural body, and there is a spiritual body.
1Co 15:45 And so it is written, The first man Adam was made a living soul; the last Adam was made a quickening spirit.
1Co 15:46 Howbeit that was not first which is spiritual, but that which is natural; and afterward that which is spiritual.
1Co 15:47
The first man is of the earth, earthy: the second man is the Lord from heaven.
The first man Adam was earthy. That is another way of saying he was mortal.
1Pe_1:24 For all flesh is as grass, and all the glory of man as the flower of grass. The grass withereth, and the flower thereof falleth away:
This speaks of the flesh made from the dust, intended to wither away.
1Co 15:44
It is sown a natural body;
it is raised a spiritual body. There is a natural body, and there is a spiritual body.
1Co 15:45 And so it is written,
The first man Adam was made a living soul; the last Adam was made a quickening spirit.
1Co 15:46
Howbeit that was not first which is spiritual, but that which is natural; and afterward that which is spiritual.
1Co 15:47
The first man is of the earth, earthy: the second man is the Lord from heaven.
This does not only apply post fall because Paul is using Adam as the example of the first man who was Earthly, having a "natural body" as opposed to a "spiritual body". Verse 46 makes it clear Adam was NOT in the spiritual body when he was created! This is evidence that Adam was in a mortal, natural, earthly body and NOT in a heavenly, super natural, spiritual body.
Is there anything in Genesis that would tie it together?
The two types of death that are not specified but did take place. The death from the sin was to happen that same day but they were physically alive. The NT speaks of living people as dead so there is a spiritual or symbolic death that exists separately from literal death of the body.
Second, the tree of life is protected from Adam so he cannot eat and become immortal which shows he was not previously immortal.
You have piqued my interest in 1 Corinthians 15. I need to look at it more closely.
I included more of that so enjoy.