About 15 years ago I thought I should have a crack at understanding Wagner's Ring Cycle. I've hardly scratched the surface. Mind you, it took him 26 years to write the four 'music dramas' that make up the cycle. About 2 years per completed hour.
In many ways, the Ring is the prototype for many of today's films, and even the 'wall of sound' used in rock concerts. Almost everybody has heard the stirring "Ride of the Valkyries"!
To understand who the Valkyries were, you need to have some idea of the Norse and Icelandic sagas. That's before you try to see how Wagner twisted the plot lines and merged characters to underscore the human foibles of greed, betrayal and world domination.
Throw in the Greek tragedies and a bit of Shakespeare as background.
Musically there are hundreds of 'motifs' or theme music fragments which give clues to the plot line. Fully understand - never. Appreciate - usually!