So I won't actually answer the question in the title. I'll let someone more qualified do that. Among my favorite "world jazz" artists are a number of Africans: Hugh Masekela, of course, and Richard Bona, Suthukazi Arosi, Gangbe Brass Band, Henri Dikongue, Dorothy Masuka, Abdullah Ibrahim (aka Dollar Brand)...the list seems endless.
One of my favorite African musicians is not commonly described as a jazz musician. Heck, he's not commonly mentioned at all here in the US, despite his tremendous chops and even more stellar compositions. I've written about Louis Mhlanga in a previous post; here he is with Dutch bassist Eric Van Der Westen, on a sublime CD released in 2000. Is it jazz? You decide.
[mp3] Louis Mhlanga & Eric Van Der Westen:
from the album Song for Nomsa (the only source I've seen for this album is here)