I agree that elves have been given too much. And as a species, they are no better and don't have to live longer than anyone else. Of course, we shouldn't forget about supernatural beings. Dragons, maybe. I would turn to a study of actual biology. Whales with sharks of some species can live 200-400 years. Jellyfish are technically immortal. If you come up with creatures with long lifespans, they should have enough differences.
Intelligent beings that live long enough become objects of worship. In a story, they can be used as the basis of a mystical world, a story, or a pillar that maintains a complex balance in the world. If there are no such creatures, they are replaced by monuments, relics, and the like. They can convey so much more than books. But they can probably be the cause of slow development or no progress at all.
Unreasonable long-livers will exist more for beauty and to emphasize the singularity of the world. Authors using the species of elves often forget that they are mystical beings, not the usual subspecies of humans.