Facts dictate there are people and these people have different appearances and cultures.
I think usually when people say that race doesn't exist they don't mean that
ethnicity doesn't exist. They just mean that there's no particularly good reason to think that "white" people from Iowa share a lot of common culture with "white" people from Finland, or that "black" people from Milwaukee share a culture with "black" people from Tanzania, despite their superficially similar appearances. The point is that culture (i.e. ethnicity) is far more important and also varies in many ways which "race" doesn't capture at all.