What about Huck??? :-)
He's an intriquing character, and difficult to figure out. Part of the problem is that I haven't read all of Mark Twain's books, and I understand that some of the characters changed throughout these books as Twain acquired more of a dim view of humanity over time.
Of course, my favorite "American folk hero" of sorts wasn't exactly a folk hero -- he was a real person. If you have the opportunity, you should read about NASCAR legend Junior Johnson to see the kind of impact that a simple, humble (but incredibly smart) man can have.
If nothing else, I'd say that a guy who is arrested by the ATF and serves 18 months in prison for running moonshine -- after his NASCAR career had already taken off, mind you -- is all right in my book.