Darwin was very anti-racist by the standards of his times, born into a society so deeply suffused by racism - having practised slavery, which Darwin despised, for centuries already - that even people firmly on the anti-racist side of the Overton window like Abraham Lincoln (who, by the way, endorsed Darwin’s theory) retained views that are rather racist by today*s standard.
Historically, racists have often been very uncomfortable with Darwinian evolution and the universal kinship of humanity that is implied by it. In fact, the Third Reich, Dixie segregationists and the Apartheid regimes all suppressed its teaching….
And it is not as if Europeans needed needed evolution to designate sub-Saharan Africans as subhuman primitives. The fun thing is, one of the arguments in favour of this could well serve as a Creationist example of the perils of abandoning *sola scripture* Biblical literalism in favour of theological speculation, but you barely see Creationists doing so…
PS:
Also:
- The notion of some creatures being more evolved and thus superior is a crass misinterpretation that is rooted in firmly pre-Darwinian, partially Christian, ideas that persisted due to their deep entrenchment in European, and especially Colonialist, thought.
- Science seeks to describe the world as it is, not as it ought to be, and the possible moral consequences of a scientific notion has no bearing on its truth.
- Evolution is not a religion based on the revelations of an exalted prophet, so the character of Darwin is completely irrelevant to modern evolutionary biology, anyways.