Redguards looks more like Arabs to me... scimitar, turbans?
EDIT: and i dont mean to offend anyone i am part arab
Redguards are based on the Moorish culture specifically.
Bretons are Britain.
Khajiit are loosely African based.
Argonians are just plain weird, but I get a distinct Vietnam feel from Black Marsh.
Nords are Scandanavian, Vikings, Nords. Not much else to say there.
Altmer are Asian, closest to Japanese.
Bosmer are kind of traditional Elves that live in forests and shoot bows (plus cannibalism).
Imperials are ancient Romans and classical Greeks.
Orcs are your generic tribal Barbarians, with some Scottish highlander influence.
Dunmer are the most unique culturally. Somewhat Asian like all elves, but still very alien to anything on our world.