Archie Green at one time had some information which placed the actual John Henry in Alabama. He asked me to work on the search with him, but we never came up with anything other than an attributive reference which, by the nature of folk music, is more likely to be wrong than right. Bert's information is most likely correct. Alabama will just have to be content with Railroad Bill as a ballad hero.
I suspect that you're better off not trying to stuff the piece with a lot of symbolism, or to read anything much into it other than what the words suggest: a kind of American Luddite ballad about a man whose pride in his work and whose ego caused him to challenge the advent of mechanization.