When a jack donkey meets a mare you might get a mule. In real life the mule is usually sterile. In fiction the mule can be the creator of worlds. For why not?
Hold that thought.
Nonhuman characters throng mythologies and religions in symbolic roles. Lions, eagles, horses, snakes, dragons and their kin. The powerful, the swift. What about the stolid or the fickle?
Perhaps the most easily forgotten are those who carry the world on their shoulders, unseen. (Not Atlas, though, he’s had his fair amount of press coverage, even siring a common noun.)
I remember the weird plausibility of Terry Pratchett’s idea when I first read it: four elephants carrying his Discworld, while standing on a turtle that swims through space. The notion may or may not derive from anecdotes in Hindu mythology.
Telescoping world-holding responsibility appears elsewhere too. For example, going back a few centuries, there are Kujata and Bahamut, a bull and a fish, whom I discovered through Borges’s Book of Imaginary Beings. Here’s how he introduces them:
In Moslem cosmology, Kujata is a huge bull endowed with four thousand eyes, ears, nostrils, mouths, and feet. To get from one ear to another or from one eye to another, no more than five hundred years are required. Kujata stands on the back of the fish Bahamut; on the bull’s back is a great rock of ruby, on the rock an angel, and on the angel rests our earth. Under the fifth is a mighty sea, under the sea vast abyss of air, under the air fire, and under the fire a serpent so great that were it not for fear of Allah, this creature might swallow up all creation.