The Trilogy is really an introduction to Tolkien's created world. He'd been creating a mythology his whole life, published the hobbit as a story he told to his children - a dipping of a ladle into a very deep pot. The same was true of Lord of the Rings. The publisher wanted more books, Tolkien focused on one part of the tale and sold that.

Tolkien knew Latin, Old English (His translation of Beawolf is still considered one of the best), Greek, and Icelandic. He read the myths of Europe in the original languages. Many of his character names can be found in these ancient texts.

He and C.S. Lewis were at the same college and were members of a weekly literary club, where they had srong arguements about the role of allegory in fantasy novels. Tolkien wrote a great essay called "On Fairy Stories" which established the basic formula for the genre.