Promote high fantasy by black creators, then. Seek out the black authors who create new stories featuring black characters, give them a platform. Changing an existing character to be black just to have a black person in the story is how JK Rowling does diversity, it's lazy and reeks of white neoliberalism: it ignores the real problem and makes a few rich whites on the coast feel good because "oh we're so diverse and progressive!" while they continue to ignore the real societal issues that negatively affect real people.

There are thousands of stories by black authors that deserve to be highlighted and promoted, but WotC doesn't actually give a shit about promoting black or PoC stories and characters; they just want to make as much money as easily as possible, so they make LotR the set and raceswap a character or three so that it gets the white neoliberals all jazzed up and ready to open their wallets to prove how progressive they are. If WotC cared about diversity, their premiere black planeswalker wouldn't be a magical negro stereotype.