We will probably never know who was the first Black creator to adapt Lovecraft to the medium of comics. Pre-Code Lovecraftian Horror Comics rarely credited their writers and artists; it is not impossible that one or more uncredited toiler in a small horror comic shop was Black. So too, there may be some obscure comic that hasn’t come to light yet where an early artist or writer applied their talents to a Lovecraft adaptation that has so far escaped notice. Such things happen, and when they come to light push back “first” a little further.
That being said, the first Lovecraft comic adaptation by a Black creator that I’m aware of is “H. P. Lovecraft’s The Ter’ble Old Man” in the underground comix Laugh in the Dark (1971, Last Gasp), by Larry Fuller.
Quick! Someone give a smartphone to Mount Etna!