Monotheism among the ancient Hebrews evolved from a little known legend. The father-God, El, gave each of his sons a human tribe to call his very own. Yaweh got the Hebrews, and so they were obliged only to worship Yaweh.
Also stories that are thought to be uniquely Christian are often anything but. The story of the Great Flood? It' common these days to hear it was probably inspired by an actual event like a flooding of the Black Sea Basin, but no, it started as an explanation for huge ruined and abandoned cities found in Mesopotamia, the remains of Assyrian cities long forgotten whose destruction was explained as the result of some terrible fllood in times past. A legend of a flood survivor arose - of course that had to be enough survivors to explain why anyone was still alive, and the Hebrews incorporated the myth with their own version, a practice not unusual in the ancient world.