It is common in isekais anime for the protagonist to die and be reincarnated in ANOTHER different WORLD where everyone is white and Asian. Generally the protagonist is a Japanese person who was reincarnated in a fantasy world based on European mythologies in which he starts to live with elves, fairies, elves, etc.
So my question is: how likely is it that someone would complain about a story that takes place in another world where all the characters are black? Would a fantasy story based on African mythology be subject to complaints?
So, there’s a number of furry works that don’t have humans at all, but I don’t think that’s what you’re asking (and isn’t really that weird even for people outwith the furry sphere).
I’m a white person who, to be honest, isn’t really that knowledgable about many cultures. I’d personally love to see media exploring african mythology. It would certainly be more interesting than all those reskins of greek mythology.
There’s, sady, a group of people that want to deminish and erase history of non-white races who would almost certainly complain that you’re being too “woke” or whatever. I’d ignore them, and focus on building your world with the respect and dignity that it deserves.
Just avoid having black people (and other marginalised groups) be used to fill up a “diversity quota”. That kind of thing is obvious and just generally feels lazy.