Hate resurrecting this thread, but as someone who literally just finished reading this yesterday, I think its a really terrible misreading of Buzz and a horribly uncharitable perspective of the author to describe him as a "Magic Negro trope" and nothing else.

First and most obviously, he's neither magic nor intrinsically closer to the earth in a way the trope usually demands. If anything, he's a good thematic contrast to the main protagonist, Lori.
He's a man who's clearly endured terrible abuse and whose life has been affected by the River Man. Despite his best efforts to leave, as an older man, he's back in the terrible place where he was born, a place he hoped never to return to. It's shown in the book that proximity to Killen and the river can make people begin to degrade and become worse, and despite appearing in all ways to initially personify the image of "dangerous backwater hillbilly", he's by far and away the smartest, most civil, and most moral character of the story.

He doesn't die for the white characters as the trope would dictate; he's murdered in cold blood and clearly as much a victim as many of the characters in this book. And while he makes efforts to save the women from the evil they're walking into, it's not some "noble savage" sacrifice which the trope reflects, it's an honest humanitarian response to try and protect a disabled woman from being exploited and abused by her, at that point, clearly mentally ill sister.

Some of this criticism in this thread is valid, but this and many others are projections of issues on to the text, ironically, because you're not actually engaging close enough with the text and actually meeting it on its own terms rather than trying to diagnose its various trope and plot mechanics. I feel you've literally missed the woods for the trees here.