Let's build some demihuman cultures. Choose one descriptor and apply it to one species. The descriptors describe the culture's role in its environment; the species define its history and proclivities.
Green: Species with this descriptor are master manipulators of the world's flora. They live in the lushest biomes, like remote forests or steaming jungles, anywhere with a surfeit of growing things. Gardeners, stewards, perhaps, or when in a more sinister mood, letting their domain run riot, a biome that slowly strangles, throttles, overgrows. When provoked, green species retreat into the maze and let the land itself isolate, confuse, and exhaust interlopers.
Bane: Bane species have one eternal enemy that gives them their raison d'etre, stemming from an ancient feud or outrage that can never be wholly paid back. They are mad, bad, and dangerous to know, but as allies, can eliminate your common foe with extreme cruelty and relish. Join their cause, and they love you, providing you are just as fanatical and willing to compromise every core value you might possess to kill a few of "them." Anyone else is at best, irrelevant, and worst, a speed bump on their road to revenge.
Deep: A deep species lives below the floor of the world, either literally or figuratively. Many do live in the underworld or at the bottom of the sea, but some live in the underworld only the the social sense, a community apart and largely unseen, perhaps considered mythical by most surface dwellers. Deep races value privacy, carefully cultivate misinformation about themselves among other species, tend towards paranoia, consider banishment the ultimate punishment, and often labor on a huge project or scheme that cannot, in fact, must not, ever be realized, for if it were, their reason to be would cease to exist.
Iron: The role of a species with this descriptor is to gather and maintain strength without concern for the happiness, satisfaction, or freedom of its members. Something happened in the distant past that decimated them, and now their mantra is never again. Weakness is fatal, dirty, disgusting. Iron races generate vicious, bloody internal purges of the weak and unorthodox, fortify their borders, and prefer to plunder, steal, or do without resources rather than trade them. Tradition, lineage, and ritual matters dearly, a constant and severe orthodoxy. Leaders tend to be dictators or strongarms who rule by fear and force, always looking over their shoulders for the next bully.
High: A culture deemed "high" sees itself as the paragon of its species -- conservative, regal, yes, but also hidebound, perhaps inflexible. It may tolerate rustic or mongrel offshoots of its species as long as they don't question the supremacy of the "pure" strain, but more likely, they will look at other cultures of their kind as bumpkins, impure, somehow tainted. At their worst, they may seek to eliminate members of their species whom they deem faulty or subpar.
Feral: A feral species is often a "high" culture gone wild, or a group of renegades or escaped chattel living in the wild after escaping from captivity. This descriptor indicates a intimate relationship and encyclopedic knowledge of its territory, small-scale organization into bands, gangs, or tribes, and an imperfect or mythologized understanding of its own past. What little they preserve or remember about their formal existence may be revered and ritualized, including artifacts or keepsakes from times past.
2. Match your chosen descriptor to one of these species/races:
Elves: Elves made the living world and aren't happy with what the younger races have done with it, or else they were simply the first sentient race and believe that the other races can't possibly appreciate the beauty of it all as deeply as they do. Elves play the long game, being nearly immortal, and have trouble feeling the urgency of any issue that isn't an existential threat.
Dwarves: Dwarves see themselves as superior to elves because they made the very foundations of the world -- its mountains, valleys, and abysses. Elves just gussied it up with greenery. Like elves, they are long-lived. In some worlds, dwarves didn't just make the mountains; they are literal of the rock, either being born as natural stone formations in deep caves or carved out of stone by the elders of their clans, essentially golems made by golems.
Humans: Humans are notable for their adaptability and short memories. The elder species of the world would say that these two qualities are undoubtedly linked and in fact mutually beneficial to these prolific upstarts. Humans find niches everywhere, and compensate for their rather fragile, short-lived physical form with ingenious technological innovations, complex social fabric, and zest for procreation. As a consequence, they tend to fill any volume they are dropped into, then push out across the frontier to repeat the process. Other races tend to resent them even as they find themselves charmed by them.
Orcs: Orcs certainly didn't ask for the job of being the ugly, brutal race created as soldiers and laborers of an evil god. But it's all they're suited for, and they lack the imagination to reinvent themselves as anything else. Orc-only cultures are quite rare. It's hard-wired into their nature to serve an overlord who can do the thinking and planning for them, so they can focus on the enjoyable tasks of destroying, plundering, and enslaving. But occasionally a band of orcs finds itself between gigs for a few centuries, and may develop into an independent culture before being cowed into serving yet another brutal warlord or diabolical sorcerer.
Gnomes: Little gnomes are secretive -- it's in the root of their very name. Contrary to common wisdom, they are nothing like dwarves, being of roughly human proportions, albeit much smaller, with pointed ears and somewhat outsize heads to accommodate their prodigious brains. They revel in secrets, schemes, and plots, being too small to confront or safely treat with other races openly. Like humans, they are prolific and adaptable to nearly any environment, even to some places that humans won't tread, like the deep abyss. Their technology puts the other races to shame and is on par with the most impressive elven magic or human sorcery.
Readers, let me know what other descriptors and races you come up with and how you use this stuff.