I think of my world Refuge as being a very imaginative creation. I created kingdoms, continents, oceans, all very detailed. I filled in a history and then blended it with our own history, the product of millions of modern Earth people being transported to the world with their cultures and traditions. I decided that the concept of our fantasy archetypes originating on this world was also cool. I tried to fill in a little of this background, using the names that readers would be familiar with. When I sent the original novel out to publishers and readers in the late 1990s one of the comments I received over and over again was that I was using the same tired old fantasy races, Elves, Orcs, Dwarves, Halflings, and whatever. So when I did the updated novels I gave the races their own names, as well as the ones the transported humans gave them that fit their own conceptions of those creatures. So I still had elves, high (Ellala), forest (Conyastaya) and dark (Dikefin), and the dwarves (Gimikran, Dimikran, and Kidimikran), orcs (Grogatha) and others, and gave them evolutionary backgrounds that linked them to humans. But they still had the traditional names as well as the new names I made up for their own representations of self. So why even use these traditional names. Because that is what the humans would call them after seeing them. I think over ninety percent of humans, on seeing a slender fair humanoid with green eyes and pointy ears would immediately think of an elf. Or on seeing a squat muscular creature with a beard would think of the term dwarf. There was a world building article out years ago about how some authors would describe a long ear, furry, hopping herbivore on another planet as a Smeep. When anyone hearing the description would think rabbit. The point of the article was to use the common name instead of something made up when it was the common creature being represented. It made it less confusing to the reader.
So what about mythological type creatures? If the creature is fair skinned and pointy eared does it matter if it’s called an Ellala, an elf, a Melnibonean or Eldritch. Or if it lives seven hundred years, seven thousand, or is immortal. Most people would call it an elf, and it would seem natural that it live in the woods. Its ebony skinned brethren would make sense living underground, as would squat, heavy muscled creatures that we would call dwarves. They might be called different names in different works, but they are still dwarves.
I see this all the time in newly released books, even some that are put out by major publishers. They have a race of squat, powerful humanoids who are great miners and smiths. They have a different culture, maybe a different affinity for magic from other races of fantasy. Maybe they are scrupulously clean, not dirty like many fantastic dwarves. But they are still dwarves by any other name.