an allegory
Examples
As headstrong as an allegory on the banks of the Nile.
Each character is an allegory for every aspect of human existence.
A fairytale is not an allegory. There may be allegory in it, but it is not an allegory.
All perishable is but an allegory.
An allegory is not meant to be taken literally. There is a great lack of comprehension on the part of some readers.
You can make the Ring an allegory of our own time, if you like: an allegory of the inevitable fate that awaits all attempts to defeat evil power by power. But that is only because all power magical or mechanical does always so work.