I would say the moment Adam ate, sin entered the world, the kosmos and at that moment Adam brought forth for all to come after him to come forth as, dead in trespasses and sins for all would sin because it had been brought into the world, the Kosmos.
God had formed the body of Adam from the dust of the ground breathed into the nostrils of the body spirit of the breath of life and the body being sustained by the spirit of the breath of life flowing through its blood became a living soul.
Adam after eating was a living soul, dead in trespasses and sins, meaning when the spirit of the breath of life departed from him he would be dead. The body without the spirit is dead. As God had told him, "Dying thou dost die." The body returned to the dust from whence it came and the spirit returned to the God who gave it.
Adam would then be a dead soul.
I do not know whether Adam became fossilized or not.
That was the destiny of man.
However before the foundation of the world, before all that above had taken place God had determined there would be one as a lamb without spot and without blemish, sinless, who would shed his blood, who would die the death that would be brought forth by sin. That lamb would be the very, or shall we say, the only begotten Son of God.
The same God also made a promise. The hope of eternal life.
but has been made manifest now by the appearing of our Saviour Jesus Christ, who has annulled death, and brought to light life and incorruptibility by the glad tidings; 2 Tim 1:10 Darby
But God raised him from the dead: And as concerning that he raised him up from the dead, now no more to return to corruption, he said on this wise, I will give you the sure mercies of David. Wherefore he saith also in another psalm, Thou shalt not suffer thine Holy One to see corruption. Acts 13:30,34,35
Who was the promise of God for?
BTW to crossover to another thread.
God had determined there would be one as a lamb without spot and without blemish, sinless, who would shed his blood,
That is when he was set forth as, Propitiation.