This is definitely a novel, too long even for a novella. I read it at least four decades ago, maybe five. Therefore it is a quite a bit fuzzy in my memory. The book might be even older than that.
It is a space opera, with interstellar travel. There are many humanoid species (or varieties, since they seem to be interfertile, at least in a sort of "continuous" way) in the galaxy, I am not sure whether they were different to start with and met when space travel started, or all descend from "Earth human" but evolved away from the original type with time.
Anyway it is not at all PC as the "Earth" humans are a standard of reference, and the farther a humanoid is from that standard the lowest its status. I think that "gooks" were the lowest in the hierarchy, very far from humans, and "geeks" were closer to humans thus higher, and "pure humans" on top..... except that those who claimed to be "pure humans" were really always a little bit geek halfbloods, or quarter-bloods or 1/8-bloods... But it is quite possible that I interchanged the names geeks/gooks. (Of course, geeks have nothing to do with our present understanding of this word ! That was decades ago !!!)
At some point one young guy appears among the geeks and the gooks. I don't remember where he came from and how they found him, and some gook or geek notices he is really pure human, but precisely he is not prejudiced and he is looked at as some kind of Messiah (and no, this is definitely not Dune)..
I forgot the end, but somehow the fact that he was a nice guy was important.
Does this ring a bell?