What if there was no Original Sin??

We all know the story about Adam and Eve. We know that they were told not to come near a certain tree but were lured to doing so anyway. We also know that this was the first human sin.

What i want to know is : What would happen if Adam and Eve both obeyed their Lord and stayed away from the forbidden tree? Would the effects be as drastic as the concept of sin never existing? Or would it just be a matter of the descendants taking care of it? Common sense would speculate the latter, but I just can't help but wonder: Would sin have even existed?

Metaphysically speaking, the non existence of sin is preposterous. If the idea of sin never really dawned upon mankind, who's to say we would still be here? What is a mortal without sin?

Human beings are all considered the children of Adam and Eve. In that case, would it be logical to speculate that if the sin of the storied apple tree was not committed, the descendants of these beings would in turn be just as obedient to their lord?