One interesting thing about BECMI and AD&D is that they do have options to pick races other than humans and classes like bards, druids, and paladins, but the rules are always trying their very best to keep players from playing anything but the most stereotypical characters. Human fighter, human cleric, human thief, and human wizard. If you want to play nonhuman characters, you're level capped at 4th or 6th level (2nd edition was significantly more permissive about that) and to play nonstandard classes you need to roll amazingly high stats. And you can't do both.

It's still a mystery why D&D tried so very hard to make sure that everyone plays the most stereotype characters possible, but it would fit together very well with the spell lists making sure that clerics and wizards are being played according to type with no stepping out of place.