The fallen man is not a standard of humanity in any shape or form, but only something less.
In regard to the human nature vd humanity, the first Adam suffered the fall from his sin and the consequences were also passed genetically to all seed of the first Adam. Of special note is the second Adam, also human and pure, qualified to become the perfect sacrifice in response to the sin of man.
All humans since the 1st Adam other than the second Adam have been composed therefore with a fallen nature, an old sin nature, a natural man, that touches upon both the body and the soul, with a spirit that requires regeneration prior to being alive.
We therefore stand condemned before we have ever been saved, in regards to our thinking and our bodies.
Combined with other things I have learned, I take this to mean that you are saying that man was ordained to be physically immortal. Is that right? If so, is there any teaching on how man would have ever been able to go to heaven? Or, presumably, would mankind have remained on earth forever?