King Mwanga II of Buganda, whom he cites an openly Gay African ruler was rather complicated historical figure. He also had 14 wives & multiple children, kept a Harem of underage boys, & routinely executed men who rejected his sexual advances. https://twitter.com/bloodedmelanin/status/1387464541282480133

As for cave paintings depicting homosexuality in Zimbabwe, they're from the Ancient San People of the Kalahari & have been interpreted by different schools of thought to mean several different things. Here's a drawing of the cave paintings so you can decide for yourself

Was there homosexuality in Africa before Europeans? Simple answer; Yes. Most notably among the Imbangala people of Central Africa. But, Imbangala culture was so complex & layered that it really can't be properly explored & examined from our western worldview .

The Imbangala were a wholly militarized society which existed for the sole purpose of waging war. They didn't differentiate between males & females. Men & women served in same roles.They didn't allow childbirth, they grew their numbers by raiding & kidnapping young teenagers.

An Imbangala man could marry multiple men or women, an Imbangala woman could also marry multiple women or men. Even after they came in contact & began trading with Europeans, it was noted by Europeans that some Imbangala men preferred wearing western style female attire

And some Imbangala women also preferred western male style attire. Imbangala culture was pretty much destroyed in warfare with Queen Nzinga of Ndongo & Matamba, so, barely anything of it survives today.
I did a thread on them which you can check out https://twitter.com/xspotsdamark/status/1218396876942331904?s=19