You should keep in mind that Col. Pladoh is the person who insists that lady dwarfs wear chin wigs.
I prefer to keep the non-humans in check through in-game measures. Where elves are concerned...
Elves have a much smaller population than humans. They're also not as intellectually and culturally flexible as humans. Smarter, but not as flexible. They can think of an answer faster than a human, but they are not as adaptable. Think of it as a race-wide high functioning autism.
Elves are also aware of the human need to be in charge. So the elves have agreed to let humans think they are running things. Elves will take care of things behind the scene, using humans as cover for their activities. Something which greatly amuses the dragons, who have been very successful in convincing the elves that they, the elves, are running things.
Level limits are set not by a rule, but by the player. A player can advance a character for as long as adventuring with that character remains interesting. If adventuring with a character no longer has appeal, the character is retired and becomes a Game Master Character. A possible contact or patron for the players.
The Drow are another story.