There's horror and there's horror, isn't there? I donlt consider slasher movies (even those with supernatural elements) as horror - they're thrillers. Same goes for Saw and it's progeny. I watched the first one and spent three day wondering what Afred Hitchcock would have done with the same or a similar situation.
To me, Horror must be about something from Beyond or Outside, menacing ordinary humans - regardless of their skin-colour or culture. Poe, Lovecraft, M R James, Arthur Machen and others have captured this. Ghosts come from Beyond, Werewolves and Vampires from Outside the boundaries of species and humanity. The relentlessly stalking, undying Thing, whether it be Frankensteins' Monster, a mummy, a Xenomorph (for all Aliens SF trappings, it's a horror film) is both beyond humanity and an outsider.
Many of these figures arise from mythology and folk-tales. But apart from the over-used Zombie trope, most of them come out of European folklore.
To find a voice for Black horror that is not dependent upon whiteness for its' effect, it might be useful to delve into Black folklore.
What supernatural creatures of darkness slithered and stalked around slave compounds and African villages? I know that there are legends of the were-leopard (what used to be called by white people the Ju-ju Leopard), but what else might be out there? You'd know better than I!
Or you could just say that daft Englishman has missed the point again!