I wonder why gods put different races in earth, its clear that eventually these races will mix one way or another. Why not putting one race per planet? Jews already are big problem.
Great things like advancements, important civilizations, progress--they are built on collaboration between individuals.
Now, if there were only one race, with its own advantages and weakness, it would have only them and no more than them. If two whites or two groups of whites (Germany and Italy) were to coalesce, they would still be left with the limitations of whites and no additional merits over the individual white groups.
If the human species is subdivided into racial human groups, that is, groups of individuals with different strengths and different weaknesses compared to other groups of individuals, they can effectively cooperate and overpower the weaknesses they inherently have through the union of strengths.
A trivial example that does not necessarily have to do with specific races.
A person who is very smart by genetics, but by genetics itself for some reason can only be weak physically, allies with one who is very strong physically, but not too smart. Together they are both very intelligent and very strong.