They gave their ancestors (particularly their inventive ancestors) the position of god, demigod, hero or man based upon the degree of their discoveries. If for instance, someone invented music, they would become the god of music. If someone invented a subset of this, for instance a flute, they would be honored as a demigod. If they invented a lesser thing, such as a particularly beautiful song, they would be a hero. Many of the gods were great inventors and are described as so in the ancient writings. Even the Egyptians recognized much of this. They divided their own history into four ages. The age of the gods, the age of the demigods, the age of the heroes and the age of the pharaohs.
Now in ancient Britain, the gods were found in the hundreds. They would also be an ancestor honored with godhood. Their domain might simply be over a particular stream or well, or perhaps a village, or if they were significant enough to the entire tribe, they would be a great tribal god. But in truth, the gods of old were mere men and women who were honored with godhood.
This is how they are portrayed throughout the Guiamo Chronicles and I think the reader will find this very intriguing.