D&D has three classic "demihuman" (ugh) races, which have accumulated some fairly generic lore over the years. Consider the following as one way to re-flavor dwarves, elves, and halflings while keeping their core conceits:
Dwarves aren’t greedy; rather, they are addicted to finding. The joy of a dwarf is the joy of discovery, of excavation, of beholding the unearthed. That curious, proximate joy can be measured by the length between an object’s disappearance from the world and its dwarven rediscovery. An item recovered after a few years of laying lost will give a dwarf a momentary, fleeting shiver of pleasure, but a dwarf can be sent into paroxysms of jouissance at the uncovering of an item from a long undreamt past age. Nevertheless, all findings, even climatic rediscoveries, are transient pleasures. A dwarf must seek the forgoen anew and hope to find something even more elder and misplaced in order to simply feel. For this reason, dwarfs are most commonly found within the Sea of Rust, where they mine the silt of decay for remnants of eras now past.
Those who are now elves were once gods. Among the fey they were peerless; they were worshiped by goblin, sprite, and leprechaun, and that devotion transformed them into divine manifestations of Faerie itself. But when men arose and prospered upon the Earth, they did not deign to bend their prayers to the dimly-perceived elves of Faerie. As men grew in numbers and asserted belief in their own gods, the elves grew weaker until they were reduced in mystic strength below the fey that once offered them blood sacrifice. This diminution of status from godling to long-lived mortal drove the elves mad; each elf possesses a sliver of retained divine intelligence, but it struggles against confinement within the contours of a mortal brain. All elves are haunted by the memories of their former godhood. Worse yet, these memories are not just recollections of the gloried past, but also persistent reflections of the future and of presents that represent other, unfulfilled potentialities that will never come to pass. The elven mind struggles to sort through this confusion of omniscient experience and remain present in the moment-to-moment flow of time—to others the elves seem hopeless fey and lost in the tumult of their own lost transcendence.
Halflings are not born; they are made by the dark magic of hags and left in place of a stolen human child as a changeling. The viciousness of hags is legendary—they rear the pilfered child as their own, raising them to be pawns in their war against humanity, and leave a halfling behind as a joke on the bereft human parents. Indeed, the name “halfling” is a cruel mockery: their stunted bodies are only half at home in a world made for larger folk and as their inhuman parentage is discovered they are destined to only find half as much love from their foster parents as the natural child would have been given. To be a halfling is to be Byronic, morose, and desperately ravenous for more of everything that is denied them; halflings live in a constant existential morass of half-emptiness—nothing satisfies, nothing sates, and nothing fulfills. They seek half again as much food as the hungriest man, half again as much adventure as even the most curious explorer, and half again as much wine, pleasure, and love as the most debauched libertine. They are both a satire on mankind and a satyr of mankind.