I was just reading another post wherein someone commented about wanting a "black" Bespin Guard, and some kind of automatic response kicked in and I immediately mentally corrected him with (whisper) African American.
First, I've always thought that that kind of deliniation was silly being that not all "African Americans" really came from Africa, and in fact, hardly anyone who is alive in America today has ever seen Africa.
But I digress. The silliness of my correction hit me when I realized that the Star Wars Galaxy probably doesn't have an Africa anywhere. For that matter, it doesn't have an Asia, or a Central America, or an Eastern Europe. While on one hand, it's easy to look at a Mon Calamari guy and see that they all come from one unique planet, where did all the human "races" come from in the Star Wars galaxy?
Of course, we don't know exactly how or why the races became so (superficially) different here on Earth, and that kind of understanding would go a long way in helping to explain the question as it applies to Star Wars, but did all humans there come from just one planet and then spread like locusts all over the place? Or is there a "white" planet, and a "black" planet, and an "Asian" planet, and a "Hispanic" planet? (did I miss anyone?)