The joke was supposed to be that only nazis really believe in that shit, I thought most people thought that they only technically were considered to be "stupid" just because they don't have access to the same education we do due to poverty, and if they did have access to our levels of education, they obviously wouldn't be "stupid", and that it wasn't a matter of race but just about unfortunate circumstance
Now if I had genuinely called Africans stupid just because they were African, that would absolutely be racist and I should be flamed for that