I'll give you a glimpse of one of my universes, the planet where Atlans live. Saying it that way, it sounds like science fiction, doesn't it? Yet, most of the stories I've written (or have planned) about the Atlans are fantasies. The planet is earthlike, the native inhabitants 'human'. Atlans are descended from aliens (as well as the locals), and while they look like the natives, they have powers no natives have. But only the females.
It is a combination of the legends of Amazons and Atlantis; at one point, their original island home –a 'dormant' volcano – erupts, and the Atlans scatter in fishing boats, to find new homes as best they can. I know, it's been done. Amazons have been done, Atlantis has been done, probably the two together has been done. I've heard many times, 'There are no new stories, only new treatments of old stories.' I have to hope that MY treatment is not cliché.
The origin of this 'race' is science fiction, because the original 3 'colonists' were children of alien explorers. The crew member who was supposed to 'take care' of them left them here when the ship left. I don't have a lot of stories planned for those three original Atlans; fishermen get stranded on their island after a huge storm, and the girls find themselves pregnant. They find they have 'powers' that the natives don't, and which can only be inherited by their daughters.
I have stories planned from the time of the city-state on that island through centuries of history, and even one set in what would be considered 'modern'. Most of them would be in what we Earthlings consider pre-history. With that kind of time-frame, and the fact the Atlan powers are considered 'magic', these stories wind up being fantasy. Now if I can just make them 'fantastic'!