Short answers, pulled from the story.
Tolkien stated in his Letters that death and the desire to escape it form the core theme of The Lord of the Rings. An appendix tells the tale of Aragorn and Arwen where Arwen chooses mortality after more than two hundred years of life so she can marry the mortal man Aragorn.
Tom Shippey describes the narrative as an anti-quest focused on renunciation rather than traditional quests like seeking the Holy Grail in Arthurian legend. He notes that the hero hopes to destroy an object rather than acquire one while Richard C. West calls this quest primary alongside the war against Sauron.
Anne Pienciak notes technology employed only by forces of evil in Tolkien's works causes ugliness depersonalization separating man from nature. Saruman's name derives from Old English searu meaning skilful or ingenious and Isengard described as industrial hell with wanton destruction of trees fueling machines revealing evil ways.
Tolkien professional philologist deep understanding language etymology origins words ancient myth true language isomorphic reality each word names thing thing has true name giving speaker power over thing. Hobbits ponies receive names from him and proper plurals dwarf elf must dwarves elves not dwarfs elfs dictionary printers typesetting Lord Rings would have them.
Scholars note women play significant roles book carries Christian message Tolkien consistently anti-racist private correspondence. Galadriel powerful wise terrible beauty Éowyn extraordinary courage valor Arwen gives up Elvish immortality marry Aragorn while Ann Basso argues Mythlore female characters diverse well drawn worthy respect Katherine Hasser J.R.R.Tolkien Encyclopedia gender roles Shire not sharply separated males Bilbo carry domestic duties cooking cleaning.