The Bible doesn't say how long "a long time" was, but okay so far.
Here's where your logic breaks down. His choice to sin (for he was not deceived as the woman was) IS the fall as far as you and I are concerned for we are all counted as in him, not in her. This, I suspect, prefigures the believer's positional standing in Christ, simultaneous with his positional removal from Adam.
I'm not going to argue the nature of Adam's nature. All I need to do is remind you that his relationship with God - heretofore perfect - was now damaged by his choice to sin. So it is with our own relationship with God, BY NATURE (take that as literal or as a figure of speech but it amounts to the same thing, for we ALL sin and fall short...where do we get that? From Adam).
Dead wrong. The old man is all one has and is
apart from Christ, and the old man, the flesh, IS sin.
Dead wrong. The old man can do nothing BUT sin. That's why the only remedy to Him is the crucifixion...being reckoned as DEAD. The logic of your position, to the contrary, seems to be that the old man can be tamed, trained or reformed to an extent that eventually pleases God.
Dead wrong. The new man CANNOT sin.
Dead wrong. He would have had no need to put on the new man for there would have been no old man to put off.
An offer of reconciliation assumes prior alienation. We -- all of us -- are born alienated from God by sin and so are in need of reconciliation to Him. We -- all of us -- get that alienation from Adam.
Ephesians 2:3. Deal with it.