Character Races

Players Handbook (page 13)

After a player has determined the abilities of his or her character, it is then time to decide of what racial stock the character is to be. For purposes of the game the racial stocks are limited to the following: dwarven, elven, gnome, half-elven, halfling, half-orc, and human. Each racial stock has advantages and disadvantages, although in general human is superior to the others for reasons you will discover as you read on. The Dungeon Master may have restrictions as to which races are allowed in the campaign due to the circumstances of the milieu.

House Rule

The ONLY races available for player characters are:

• Dwarf
• Elf
• Hobbit
• Human

Gnome has been excluded because I believe they are better suited to residing on top of big red stone mushrooms with a static fishing line in a genteel garden setting.
And while Half-Elf (and half dwarf and half hobbit and elf-dwarf, etc.) characters will appear as NPCs, I don't see the need to extend the available races where greater skills can be given to characters with multi backgrounds, and multi talents. Exception half-orc, because orc is not availale as a player character.
The Half-Orc would just be shunned and un-trusted in all encounters both from civilised humanoid to non-civilised monsters, and therefore they would be so rare as unlikely to be in an adventuring party.
And this is NOT 5e, so all those new, shiny looking races do not exist.

Character Class Limitations

from Players Handbook (page 13) - Character Race Table I & II & III
There are no character class and level limitations applied to player characters. That means that ANY race can be ANY class, and they can attain any level, there is no upper limit.
And the minimum and maximum ability scores by race are not applicable either.

Racial Preferences

from Players Handbook - Racial Preferences Table (page 18)
In general, these preferences are not applied in the Campaign setting.
Although that does not mean everyone is wandering around with flower in their hair proclaiming peace to everyone. Tribes of same race may have dislike, aggression or even hate for each other. But this will be more for tribal or locality reasons rather than some inbred racial preference.