He said some tribes had 15 genders. Is this true?
It doesn't even mean anything. To the LGBT community, dressing a certain way or doing a particular activity means "identifying with a gender". When you look at groups in the past through this biased and convoluted lense, any social category can be considered "a gender". Gripes of an anachronic agenda.
What I can say is that I don't know of any tribe that was confused as far as who's a man and who's a woman.
Another thing that I noticed is how much Christianism and Islam are designated as the originators of a homophobic sentiment in Africa, without any consideration for all the testimonies of African people still deeply entrenched in traditional beliefs clearly showing they hold and held the same views.