All right… here’s the gist, we sin because we’re stupid. Stupidity doesn't make you imperfect other wise lower creatures such as dogs, cats, what ever would be imperfect. What it makes us is vulnerable. Satan tempts us and we sin… just like Eve. She never would have sinned had she not been tempted… Though many people don’t like to think like this is how sin works because it leads us to feeling as though we’re easily and constantly duped and that hurts our egos… Again, a sin… Pride. Free will in reality is perfect as it allows us to have potential. Without it we’d be exactly what we were made and only that, but with free will we can use our own judgment and intuition to do what ever we want and maybe even surpass what was originally intended for us.
*As a side note, it was free will that made Lucifer fall from grace. It was the one thing he wanted most. He hated having to do, as God wanted him to. His jealousy of man made him hate. Ironically, had he not been such a high ranking angel in the first place, he’d never even have realized what was going on in the first place…
And as for asking God for forgiveness, you have to remember, the God of the Old Testament was a very different God then the one from the New Testament, at least as far as temperament was concerned. The old God was all business, Sodom and Gomorra, Noah and the Flood, and the Tower of Babble, just a few examples of what we might consider harsh treatments for disobeying. I’m sure people could ask for forgiveness, but it really wasn’t “made popular” or made known until Jesus came and basically told people that in order to stay in God’s good book, you had to apologize and basically throw yourself on his mercy.