Definitely. I’ve been thinking about this over the last couple of days, and I honestly can’t remember what are my own thoughts and what I got from here; but I’ll risk repeating what others have said with something that may help others understand.
One of the tools in racism’s toolkit is to dehumanize groups by comparing them with animals. It IS true that monkeys aren’t human, and they jump around and hoot and are playful and mischievous and sometimes from a human perspective “thieving.” So if you’re a racist who wants to ascribe these traits to a racial group, imagining that group as monkey-people is an effective way to get others to see those animal traits in that group. It’s a pernicious fantasy with harmful real-world effects; and folks who are harmed by these awful human-animal stereotypes, not to paint with too broad a brush, are generally unhappy about them.
One of the tools in fantasy and science fiction is to create new species that are sentient and human-like; and an easy way to do that is to humanize an animal. You can take an animal like a monkey and humanize it by saying, “They’re like humans who jump around and are playful and mischievous and thieving.” Your intent is 100% different from the racist’s intent. But what you create comes out looking very similar. And folks who are harmed by that stereotype? They might not be too happy about it.
Another humanized animal might be far less problematic. I’ve not heard anyone complain about the racist implications of the tabaxi (cat-people), probably because there’s not a racist history of dehumanizing people by comparing them to cats.
Does this mean that it’s cool to create cat-people, and much less cool to create monkey-people?
Yup.
“But that’s not fair!” you might say. “Why should racist stereotypes get to ruin my fun, when my fun isn’t racist?”
I sympathize with this objection to the tune of a very tiny violin. You know what? Racism sucks. It’s resulted in the murder, torture, and oppression of millions of folks, and especially Black Americans. And it might also mean that you shouldn’t play monkey-people in fantasy games.
If you don’t like that injustice, let’s work real hard together on getting rid of racism. When we’ve gotten rid of racism, Black people won’t suffer systemic oppression, and as a bonus, you get to play a monkey person without catching side-eye!