Just a few words on Tolkien. I can’t substantiate any of this; these are just recollections of things I read of him mostly decades ago.
Tolkien spent his early childhood years in South Africa. One day he was abducted by one of his father’s workers and taken to the worker’s tribe to show them what a white child looked like. There was no harm intended and J.R.R. was quickly discovered but I imagine it left an impression on him.
I know few will believe this but Strider was first imagined as a hobbit. I think I read that from one of Christopher Tolkien’s books.
As all good writers, Tolkien borrowed heavily from many sources. With his work in languages he was familiar with the mythologies of many cultures; note one of the names of Gandalf was Mithrandir. I even recognise some references to Old Testament works in The Simarillion.
But both he and C.S. Lewis acknowledged a great influence from the works of William Morris. If you read Roots of the Mountains and House of the Wolfings you will see where Tolkien borrowed some of the style and plot elements. At that time,especially since Wagner has been mentioned, I think there was a vauge romantic notion of an idealised past. The two books by Morris represented a version of that idea in the stories of a mythic Goth Tribe.