And although he isn’t unknown, especially to people who love the ol’ Acoustic Blues- Reverend Gary Davis , is not nearly as famous as he should be, His students include Bob Dylan, Jorma Koukanen, and basically every rock star who took an interest in finger picking blues who past through NYC in the 1960s or anyone who learned anything from Stefan Grossman’s Mail order Books/Cassettes/VHS/DVD guitar lessons in the past half century.

Or again not unknown ( But neither are some of the people you mentioned) But Charley Patton invented Delta Blues and his student Robert Johnson gets all the credit after a historical rewrite that began in the 1960′s. Delta Blues is part of American Musics DNA. Blues itself is the sound of the American 20th century. It was not “the Jazz Age” as it is so frequently called by sterile academics. It belonged to Blues and Blues’ and Country’s bastard step child Rock and Roll. Which makes Charley Patton possibly the singular most important figure of 20th century American music. I’d probably place him second behind Bob Dylan. Yes he gets some of the praise that is due him, but not nearly 1/10th of the credit he deserves.
And speaking of Dylan – Ramblin’ Jack Elliott is virtually unknown to anyone under 50 who isn’t a big Bob Dylan fan. That is an unsung influential artist if there ever was one.