I know very little about this story in advance, except that it has a lot of genealogical content in it. I'm expecting dodgy ancestral lines to show up too. I do know that Lovecraft had problematic family history, in terms of mental health, so it will be interesting to see where this story goes with things.
I'm curious about the collection of Wade Jermyn, but wonder how much more extreme it was than other collectors of the time. There was often a tendency for collectors then to collect trophies and specimens that would be abhorred nowadays, and I find it hard to believe that Wade was significantly worse than others in his day. But I do find it plausible that his ravings alarmed others, indeed they're very reminiscent of other Lovecraft stories.
I do like the account of the family history, but then I'm a genealogist, and never object to a story that inspires me to start drawing up a family tree.
The story rambles on too much for me though. The second portion goes on far too long, and needed judicious editing. And it's far too obvious to the reader who was what in the story of the ape goddess.
But worst of all I find the underlying idea of a degenerate line descended from Africa troubling at best, and racist at worst. It disturbs me in ways that are not a good measure of it as a story, and I wouldn't want to reread it. Having said that, the African chief Mwanu is presented with sensitivity and respect. But I still find the story distasteful overall. Even the passing idea of a European being required to find things precisely, when the Africans couldn't pinpoint it, combines with other elements to be objectionable. Just no.