The Ring of Power or The One Ring in LOtR symbolizes fascism. The refusal of Middleearth's powers to use it to fight Sauron symbolizes the refusal of Allied powers to implement more draconian, fascist practices to combat fascism. I mean, England could have become the 4th Axis power, it really was on the fence up until 1941, when shit hit the fan.
This is why Sauron is so faceless and doesn't even appear in the book, but is only mentioned!
Anyone can be Sauron, as long as the Ring, the fascist ideology, lives!
Some it would turn in antisocial survivalist bums like Gollum, some will rise to great power, like Sauron and Saruman.
And, I mean the whole rings of power being later united under one ring, being forced to bind to its power is a pretty transparent analogy of Nazis coming to power, with their puppet Mussolini (Saruman)...
The ring itself is taken from Germanic mythology, it's a very German symbol, like the Ring of Nibelung, or that Nordic magic ring that could spawn 7 golden rings a day...