"Racism" is nothing more than an extension of tribalism. It is the absurd belief that because someone looks like you, they will share your views and values.
As humans advanced beyond small, warring factions, the desire to belong to a protective group remained. In homogenous societies, you will find that this need is met by creating factions based on religion, diet, and other elements. In diverse societies, race is ofter the basis of factions because it is visible.
But anyone with a background in science already knows that "race" is an utterly meaningless construct. The variation between black and white is so infinitesimal as to be meaningless. Further, those differences are not stable. Skin tone especially changes due to environment. Afrikaners will find generations to come with increasingly dark skin. American blacks already are "fading" and becoming lighter skinned - and no, this isn't just because of intermixing with whites.
Race doesn't really exist. We are all just humans.