Answer: myth .
Explanation: traditional story, especially one concerning the early history of a people or explaining a natural or social phenomenon, and typically involving supernatural beings or events.
"ancient Celtic myths"
usually traditional story of ostensibly historical events that serves to unfold part of the world view of a people or explain a practice, belief, or natural phenomenon creation myths. b : parable, allegory Moral responsibility is the motif of Plato's myths.