I have a vague outline for a fantasy setting in my head.

Basically, there's the typical DND races: humans, orcs, dwarves, halflings, elves. The difference is that in most settings humans are usually the most populous race, as well as the "neutral, normal" race, without any glaring strengths or weaknesses.

My idea is that humans would be a plurality-minority of this world, maybe 20% of the total population. Their base of power is precarious, a handful of young kingdoms sandwiched on either side by two big, ancient empires. On one side there's the halflings, who view themselves as the "true race of man" and disdainfully refer to humans as "twicelings". They see humans as giant mutant freaks, to be exploited for labor at best and outright exterminated at worst. On the other side there's the dwarves, who view the humans with a more paternally imperialistic outlook. They believe it's their "short man's burden" to civilize the humans and bring them under dwarven suzerainty for their own good. They often clash with the halflings over influence in the human kingdoms. The elves, through some weird accident of evolutionary psychology, find the humans "cute". They often keep them as pets,(the lifespan of a human being comparable to that of an elf in the same way that of a dog is to a human) and they have a particular fascination for their exotic round ears. And orcs are just orcs, they see the humans as weaklings to be preyed upon.

Dwarves and halflings are the most populous races, being about equal, about 30% of the world each. Elves and orcs are both, for their own reasons, reclusive fringe-dwellers, so they're only about 10% each. The rest of the population is comprised of humans.