Since the thread is approaching its end I don't want to start on a course we can't continue.
I think one difference between our views here may be this "pre-fallen" and "post-fallen" state.
I agree there was a change:
Genesis 3:22 Then the LORD God said, “Behold, the man has become like one of Us, knowing good and evil
And I agree this resulted in consequences (through Adam's sin death entered the world; God subjected Creation to futility). And I absolutely agree that the only possible solution is a "new birth".
But I do not believe Adam's nature changed. I don't see Adam as a "cause" for human sin but rather a representative of mankind in that man surrenders to the flesh and sins. I believe that Adam, even when God breathed life into him, was flesh and would need a "new-birth".
I suppose you could say that I believe God's command that Adam transgressed is very much like God's Law which Israel transgressed and God's commands to mankind which we all transgress. This shows us who we are and that we need a Savior. I believe it was the same with Adam.
If I understand you correctly you have completely abandoned orthodox Christianity with regard to the doctrine of the fall of man - not only completely abandoned it but attempting to repudiate it!
There is no possible way that unfallen man needed new birth as you claim "even when God breathed life into him, was flesh and would need a 'new birth." I am sorry but that is simply false and easy to prove as false.
For example, The very nature of the new birth proves your position is wholly and totally false.
1. New Birth is a creative act of God that restores moral ability to do "good" works - Eph. 2:10
2. New Birth is a creative act of God that restores the moral image of God in man or "righteousness and true holiness" - Eph. 4:24; Col. 3:10
3. New Birth is an inward washing and renewing by the Holy Spirit - Tit. 3:5
Secondly, Romans 5:12-19 completely and utterly repudiates your position. There can be no death where there is no sin and there can be no sin where there is no violation of law. Paul argues that "death...judgement....condemnation" of all mankind was due to ONE MAN and HIS ONE ACT of sin because when he sinned all humanity sinned in him because all humanity existed as one indivisible human nature in Adam - thus IN ADAM ALL DIE. This is his argument and he proves it in verses 13-14 because death reigns over all mankind between Adam and Moses where there was no Mosaic Law and yet there can be no death where there is no law. His point? Genesis 2:13 is the law broken by all mankind existing in one man breaking that law.
Second, death during that same period of time reigned over those who had not sinned in the same similitude of Adam. Adam's sin was a knowing and willful sin unlike Eve who was decieved and it is this one act of knowing and willful sin by Adam that condemned all mankind to death even infants in the womb and/or mentally incapable humans who nevertheless die who cannot sin after the similitude (likeness) of Adam.
Paul's argument is simple! Where there is no law there is no death and yet death between Adam and Moses cannot be attributed to breaking Mosiac Law or the law of conscience and therefore the only possible just grounds for their partaking in death is they existed and acted as "one man" violating the only law given by God previous to Mount Sinai - the law of the tree of the knowledge of good and evil.
Paul denies that the plural sins of "many" are responsible for "death...judgement....condemnation" of men but that is precisely what you are teaching and are forced to adopt as you deny human culpability due to "one man" and one act by that one man.
Third, this sin and death problem precedes any moral action by all other humans even prior to birth as they are "concevied in iniquity" or in a SIN CONDITION making them sinners by nature as the cause of for later being sinners by action.
I realize why you take the view you do because it is the logical consequence of all the other erroneous views you have already adopted and whether you realize it or not you are rejecting the very heart of orthodox Christianity.