That's a lot of effort to ask people to look up, down, and behind, but absolutely not look in front, at the elephant in the room.
And the elephant in the room is the things that most directly and obviously decide how society functions, at every scale - religions, ideologies, cultures, subcultures.
Most of these are not strictly ethnically based, but they do tend to be more or less aligned on these lines for various reasons, usually more, which malicious actors obsessed about race will jump to paint as racist whenever convenient.
The "can X be part of our club" question everyone likes to ask in this realm is a red herring, because the more relevant questions are "do X want to be part of our club" and "what do we do about the X who say fuck your club, your club should be more like my old club", or "what do we do with X who don't give a fuck about our club's ideals and mission, they are just in it for the membership benefits".
Such social clubs, from internet fandoms to empires fighting wars, do fight, and the urge to fight is vital to survive in such a landscape. For if even your club's most ardent supporters say that what their club stands for is not worth fighting for, who is there to disagree with them? The competition can do nothing but welcome such attitude.
I'd also be careful of making broad statements about all people being biologically the same. There are scientifically provable differences between various populations (though the term "race" usually is usually not nearly accurate enough to describe them), usually quite subtle, but denying their existence for the sake of ideological purity only opens up any such ideology to perfectly factual criticism, and we don't want to be like the Soviet Union, do we? Are you going to tell me that the Danes and the Japanese are equally tall? W
ell that is just one of many examples of well documented biological differences, like it or not.
Funny enough, there is a simple and current example of that naturally happening.
Google photos of audiences of musical shows of radically different bands and genres. Some of them will have visibly different ethnic proportions of the audience than others. Even though the government (or even the organizer) does not mandate who can go to which one. Anyone can, they just need to want to show up and buy a ticket. But the willingness to do that is sometimes very unequally distributed across the society. That's how voluntary segregation works.