There's like two thousand of them that aren't just pidgin English, French, or Arabic dialects. Always the most insane shit ever. Whether it's tonal, has click consonants, obscene amounts of phonemes, and there's always like five more dialects of said language which are even worse! A good example would be Taa/ǃXóõ. Four tones, 58 consonants - of which up to 40 can be classified as clicking, 31 vowels, and the West variant is even more daunting. A minimum of 87 consonants and 43 individual distinct clicks. 2,500 speakers. There's African language families that are relegated to a couple hundred square kilometers in a random country, of which no other language is related to, for no fucking reason other than to cause even more conflict as nobody can understand each other. It's like Africa was struck with the Tower of Babel.
Of course, that's not ALL African languages, I'll remind you. There's some otherwise normal ones such as Amharic, a Semitic language which has a cool writing system too. When I say "What is with African languages?" I'm talking about Zulu, Xhosa, Taa, whatnot. Zulu has I think 16 noun classes, some of which are really specific and others are insanely vague.
The biome does not have the consistency to allow one species or language to travel and "win" out over the others. So specialties develop in small pockets. And with no one, short of the Zulu, conquered enough to bring some hegemony to the language in his territory, but other places stayed in their pockets or only conquered a neighbor or two before the weight of extra population destroyed the pre agricultural tribe trying to form.