Damselfly Elves
Thinking about how I would incorporate more beastfolk into my games, I was thinking about how I would turn the main demihuman races (dwarves, elves, halflings) into beastfolk. I was thinking it would be neat to have each demihuman race cover a class of animals, since humans are obviously mammals. This means we have birds, reptiles & amphibians, insects, etc.
I think dwarves should be kiwifolk: squat, flightless birds often found near caves and such (New Zealand accents optional).
I think halflings should be geckofolk: they're lizards but small and cute, whereas I think most people imagine skinks when they think of lizardfolk.
Gnomes, which I almost never use in my games, can occupy the empty slot for amphibians as salamanderfolk: a bit like halflings but not, and underwater gnomes kind of pleases me.
Finally, I think elves should be damselflyfolk (which conveniently has "elf" already in the name). These are the most interesting to me because damselflies have distinct stages of their lifecycle, and so the idea of an elf lifecycle which includes other kinds of fantasy creatures is kind of cool. Many insects' juvenile forms are called "nymphs," and I like the idea that a juvenile elf is a nymph, or "naiad," as a young damselfly or dragonfly is indeed called. Damselflies are carnivorous and seem to be voracious eaters from my cursory research, which adds to this thing I like about elves and fairies that they represent the mercilessness of nature.
In my hypothetical setting with damselfly elves, I think elves spawn in bodies of water, like rivers and lakes, and young elves have evolved to look like beautiful young women as a hunting mechanism. When people (for whatever reason) follow them into the water, they get eaten up. During this stage, which I imagine might last decades, I imagine the elves are basically at an animal level of intelligence.
Once they've matured past the naiad stage, they reach the elf stage. In real life, it takes damselflies a little while for their wings to dry and become usable. Applying the infamously long lives of elves, we can say that these are adolescent elves, old enough to leave the water but not old enough that their wings have fully developed. I imagine this stage lasts about 100 years, and is when elves are most prone to join societies of elves or other sentient beings. At this stage, elves have basically human intelligence and thought patterns, especially as their metabolism slows while they develop their wings.
Once an elf's wings finally develop, it goes through a final metamorphosis into a sidhe, looking and acting more alien as it gains the ability to fly. These elves are reclusive and strange compared to their younger counterparts. They regain the hunger of their childhood years, but they also have the ability to control their pheromones to manipulate the behavior of nearby plants and animals.