If they followed logic they wouldn't have added a black dwarf to Rings of Power, since they live almost excusively under ground. They also wouldn't have made a black elf, since they were created under starlight, before Eru even created the two trees, or the sun, after the trees were destroyed.

The only explanation that makes sense, that I've heard, for the black elf is he's a half breed, of an elf and black human. However, that wouldn't really make sense cannonically, since Tolkien made elf-human pairings incredibly rare. They were so rare, that the Silmarillion was almost exclusively about Luthien (an elf) and Beren (a human), or at least was the most important part, according to Tolkien. If I remember correctly, the children from that pairing led to Elrond and Arwen, as well as the entire Numenorian line, and kingdom, then to Gondor and Arnor, the Dunedain, and eventually to Aragorn. The Silmarillion amd the appendices read more like a history book and genetic lineage than a comprehensive story, all of which shows that elf-human pairings were exceedingly rare, and documented. Furthermore, every single description of elves says they're fair skinned, meaning white.

Still, that would require the writers/producers to know about the lore, and care about it.