Well, like I said, we're playing fast-and-loose with canon, so the exact specifics of lore and history really aren't all that important.  What matters is that it's recognizable as the character; you can mix-and-match stuff to your heart's content as long as people can look at the end result and go "okay, yeah, that's Thor."

Bear in mind that given the nature of the game, there's probably going to be little to no time for solo posting or character arcs, so if you go with Unworthy Thor, he's probably gonna stay that way.