White people is a racist term tbh.
There's so many different kinds of white, and a jew has about as much similarity to a slav as a black has to a mexican. So why is one grouped together and the other isn't?
It kinda reminds me of something a black friend of mine once said, about how they were uncomfortable with the widespread use of the term PoC because it lumps all non-white people together, implying that they're all one big happy family when clearly they're not. Specifically, they cited a friend whose Chinese grandparents, upon hearing she was moving to Toronto, warned her to "watch out for all the n***ers."
White people do benefit from the social structures in most places in ways other people don't, but the entire designation of "white" vs. "non-white" is still kinda nonsensical, as you said, when you cut it away from its context. I think historically, "whiteness" has simply been an imperialist way of designating who counts as a member of the dominant in-group; I recall someone on this very site describing the way the Irish were considered "non-white" when they were still widely discriminated against, in spite of the pastiness of their usual complexion. Hell, I've read of 19th-century racialist theories that tried to claim the Irish were descended from Africans, based on phrenology. Similarly, I wouldn't be surprised if Cold-War-era anti-Soviet propaganda played up the Asian component of Russia's racial makeup, though I haven't looked into it much.
As someone primarily of German and Irish ancestry, I find "white" to be the most convenient way of describing my racial background, since I benefit from all the privileges the category of "whiteness" entails and find experiences of "whiteness" to be relatable and consistent with my own; I know I'd be laughed at at best if I described myself as "mixed-race." I take no issue with this in an immediate sense, since I have no business pretending to face the challenges mixed-race people of non-white descent do, but I have to agree that the circumstances leading to all these designations are pretty fucked up to begin with.