For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
If not Adam than someone born later was bound to sin. God allowed the first man to fall. As always, God's plan is perfect. The universal and uncomplicated truth is that All men sin and have fallen.
An alternative outcome would not have served our Creator's purpose.
It seems to me God wanted man to eat from the Tree of Life; but it had to be man's choice. Here's why I say that: In order for there to be a choice there had to be more than one tree to eat from. But by forbidding man to eat of only one of the many trees, and then saying of all other FREELY eat, God (as he does) was guiding man towards the Tree of Life.
it seems to me if man would have been obedient, he would not have (at some point) eaten from the tree of the knowledge of good and evil. Just like God did, he would have either removed the tree from the garden or removed the man from the tree once the choice had been made. I don't believe the tree of the knowledge was the objective; it had one original purpose: to provide a choice to man.