1 If Adam & Eve did not sin, would they have moral knowledge (image of God)?
Since Adam and Eve acquired moral knowledge and therefore the image of God from eating the fruit, does this mean that they were never intended to have such knowledge? Not necessarily. God could have given them such knowledge by another means. The problem was that they acquired moral knowledge through direct disobedience and by an act of mistrust. God would have formed them in his image by giving them moral knowledge by a means other than the consumption of contraband food.
2 Was it ‘disobedience’ or ‘rebellion leading to a change in moral status’ that led to sin?
Adam’s act of rebellion predated the act of eating the fruit. While his volition was prior to the act of disobedience, it extends to the completion of the act. By this time he was already morally aware. Another way to consider the effect of sin is to view the sin factor as inherent in Adam when he was formed and the act of rebellion merely triggered a propensity to sin.
3 Was Adam alone among the male humans? Was Adam physiologically an AMH?
Adam was likely to be physiologically anatomically modern human (AMH) but certainly not alone among AMHs. His distinction was that he was the first AMH in the line of Jesus who was formed in the image of God.
4 Whom did Cain marry and who were the Sons of God in Genesis 6??
Possibly other hominids such as Homo sapiens sapiens that may not have been given the image of God. They were clearly AMH who could biologically mate with the Adamic race and probably shared in the physiology. The characteristics of AMH such as full-time bipedalism, cognitive fluidity for the development of art, science and religious consciousness, a lowered larynx to permit consonantal sound production necessary for human speech and symbolic language, as well as the capacity for self-consciousness appear to NOT be the marker of the imago Dei. Instead, the true marker is the capacity for fear and guilt, signals of true moral cognition.