Mythology is very fluid. Most of the myths are self-contradictory. You may even find four or five myths in a given culture, all giving different versions of the same mystery. Then theology comes along and says it has got to be just this way. Mythology is poetry, and the poetic language is very flexible.
Religion turns poetry into prose. God is literally up there, and this is literally what he thinks, and this is the way you’ve got to behave to get into proper relationship with that god up there.