The fundamental problem for us talking animals (humans) is whether classes are real or our inventions (ie, realism or nominalism). Intuitively, they appear to be real, but Russell’s paradox reveals that they can’t be. So, they thus aren’t real. Ie, nominalism wins.
It means that we can’t find classes, but instead invent them. This, in turn, means that race biology is unscientific. Isn’t that a pleasing fact?