In 30 years I can count the number of non-human races as characters I've ever played on 1 hand. About 5 years ago, we ran a 'monster races' campaign where nobody was human - deva, half-giant, half-dragon, drow, thrikreen, and guess what I was... an undead human fallen paladin that ended up with the Death Knight template. So even my 'monster' class was still human, just a dead one.
Throughout 1e - 2e, there were many elves in our character parties, some half elves, perhaps one or two dwarves, and one halfling (that I can recall, perhaps more, though). Still I mostly played humans exclusively. Once we got heavy into 3e, the problem with our party is that they prefer to multi-class, and we follow the 10% XP penalty for multi-classing as non-humans. (As well as the bonus feat and the extra skill points that only humans get.) So most of the party now play humans exclusively, but not for flavor reasons, but strictly due to mechanics.
I like to build 'historically' reflecting settings - feudal Japan, ancient Celt, Roman Empire, even native American, though these are fantasy worlds that emulate history, they aren't historical places redone in fantasy. In these settings human is the dominant or only playable race. These are the settings I prefer to play in, so by design preference - I only play humans.
GP