Racism takes root out of people’s fear, and that fear is genuine, although likely obscurred.
Fear that can lead to racism can just simply be a genuine “other race will hurt me” But I’d argue thats only true for the people starting out with the lowest of the low in mental capacity.
More often though, the fear that leads to racist values and occasionally genuine fear of another race is a fear of death.
All it takes is for someone a person holds in high enough reguard convincing them that death might be coming sooner because of “the others”.
And death in the broadest sense of not just a loss of life, but also losing ones way of life. From there, you can point out whatever “others” you’d like, and the bigger the group you can simply define, the more efficient it is. And the dumber a person, the easier it happens.
I’d include bigotry, sexism, even greed boil down to that too.