Why are there so many different races of human-beings?

why are there different races of human-beings? like white, black, latino, african, jamaican, mexican, el salvadorian, brazilian, samoan, tongan, hawaiian, british, australian, austrian, english, irish, etc. you get the point lol, (i hope......) like why do some of us have different skin color, hair, facial appearance, different languages, look different from each other besides some twins and triplets, etc. is it because of where we live on different parts of the world? i mean we all originated in east africa right? and then spread all over the world except antartica (i think?) are we kind of like dog breeds and cat breeds, you know like how there's dog breeds like rottweilers, pit-bulls, golden retrievers, etc. and they were bred all differently for specific reasons, i hope you guys are understanding what i mean? lol, does anybody know why we have different race, culture, and look different from one another?