A cave dweller or caveman was a being inhabiting a cave. This was not uncommon in primitive cultures.

On ancient Earth, Troglodyte was a term for cave dwellers. (TOS: "The Cloud Minders")

The early Earth cartoon Daffy Duck and the Dinosaur showed a caveman and the cave he lived in. (VOY: "Memorial")

After being stranded on Hanon IV, USS Voyager crewmembers speculated that it's natives might be cave dwellers. (VOY: "Basics, Part I")

Upon studying an Iconian device recovered from Denius III, Donald Varley described his frustration at not understanding it by comparing him to a caveman confronted with a Tricorder. (TNG: "Contagion")

Two decades after Dramia II was first hit by an Auroral plague, the once civilised planet again had cave dwellers. (TAS: "Albatross")