Yes, Adam was corruptible. He had an untested perfection. The same could be said of the angels that fell and become wicked spirits.

If Adam had chosen to eat the Tree of Life he would have been incorruptible and never sinned. Sadly he neglected that tree and chose the Tree God had warned him about. He did not take dominion over the tempting creature (serpent or whatever) but instead submitted to it, giving the domination over this world to Satan.

We become guilty and corrupt when we make similar choices to what Adam made. I do not have all the answers here, to me these are the most difficult questions in the universe. But if we, the corrupted and flawed ones, are at times enabled to respond to God's goodness, we should certainly do so. If not, our condemnation is certainly deserved.

Incidentally, it is primarily for rejecting God personally that people are lost. God comes in different ways to people, but ways that are very real to them at the time. It doesn't happen all the time, but at certain key moments. Once God reveals Himself, you are very much responsible to turn to God.

Please read some of the many testimonies on this site and use them as evidence to decide for yourself if God does exist and speak to people.