How can racism be real if race is just a social construct?

Language is just a social construct, but all people use it. Politics, also, is found everywhere that people are found, but it's just a social construct, and so is money-. Every culture has had some version of money, even stone age people. Society is everywhere that people are, and we don't survive without it-. But it's just a social construct.
Mankind is a social animal. We may make society, but we also live in it. It's really real, like sexism, class bias, colonialism and racism.