I'd go further and say that "whiteness" is just a form of the otherisum. A mechanism for establishing in and out groups to determine the potential for favorable and unfavorable social relationships. Whiteness is generally defined as people that look like, speak like and behave like a greater homogeneous population group. Each homogeneous group sets their own measure (bar) for inclusion. For instance. not all light skinned Europeans meet the standard for inclusion in small American towns. In general, the smaller and more homogeneous the population, the smaller the genetic ingroup.

>"white" as a claim of culture or heritage, only exists in the context of white supremacy. The concept of "whiteness" was invented during the days of the slave trade as a means of establishing racial classification and hierarchy - to contrast the superior "white" race with inferior "non-white" races

Isn't black exactly the same thing? A completely madeup racial category invented by white slavers to conveniently deny a group their humanity? And isn't it further possible that, after these racial groups were invented, actually real cultural identities began forming around them to the point where the invented categories had reified into something kinda real?

> to the point where the invented categories had reified into something kinda real

The "kinda" in that sentence is doing a lot of heavy lifting. It's a "real" social construct. It's not "real" in the sense of representing "real" human nature, or a "real" order of how things ought to be, which is how that social construct is wielded in practice.

Right, plenty of things are social constructs. Race, gender, laws, money. Arguing over whether these things are real or not is, I think, missing the point. The real argument should be over whether they're beneficial concepts or not.