Well, I'd quibble with your inclusion of rap, because rap by it's nature is spoken, not sung, thus has no vocal melody and isn't, in the strictest sense, singing, let alone folk singing. But Jazz, blues, choral etc...all indigenous folk/roots forms to the respective people groups with which they originated. But this raises the question of whether the originators of, say, English traditional folk songs would themselves have conceptualised their creations as "folk"...more likely they saw themselves as popular songwriters and it is in more modern times we've attached the term "folk" to their songs, in recognition of their quality and staying power.