Why do people think all humans are the same race? ?

All Humans are White if you go back far enough. Early Human ancestors started out with White skin according to biologists. dark skin evolved after Humans lost their body fur because naked skin was vulnerable to UV radiation as explained in the out of africa theory.

Think of it more like dog breeds rather than races: as Alsatian, Basenji, Bulldog and Shih Tzu are all Dog, so Sapiens, Neanderthals, Denisovans, Naledi and all the others lost to history are all Human. When Sapiens left north Africa for Europe, sub-Saharan Africa and Asia they interbred with the existing archaic human populations that were already there to take advantage of the adaptations they had made for their environment. Therefore, we are all Human, we just have slightly different mixes of human within us.

I agree. Whites are superior, and blacks and Asians are inferior. Slavs got Barbies though so we can keep them alive. They are honorary whites. If you are not European or Slavic, you need to die

I honestly don't care.

You do not know the definition of race in biology.