Are the dragons Fire creatures, or are there four kinds of dragons, earth, air, fire,water? It is a GameLit world, which are usually heavy on dragon types.
And if dragons are fire, there would have to be equivalently powerful and abundant creatures in the other elements -- whatever the abundance or scarcity, or power and weakness. A sea serpent perhaps --
Well, they could all be reptilians of some kind. I think. It's the breath weapons that seem out of place for the other elements.
There could be other foursomes of monsters of other varieties. There certainly is a foursome of humanoid races, thus settling my question of whether it should be only elves and humans.