Short answers, pulled from the story.
J. R. R. Tolkien wanted his readers to sense that the story had deep roots in the past. This goal was a deliberate aesthetic choice rather than an accidental element.
Scholars have identified Beowulf, Virgil's Aeneid, Shakespeare's Macbeth, Sir Orfeo, and Grimms' Fairy Tales as key influences on J. R. R. Tolkien. Thomas Malory's Le Morte d'Arthur and Geoffrey Chaucer's Troilus and Criseyde are also recognized sources for these techniques.
J. R. R. Tolkien creates this impression by alluding to vast backclochs including cosmological myths and mentioning objects like the Silmarils. He references characters from past ages such as Celebrimbor and events involving Éowyn to make Middle-earth feel far larger than the main plot describes.
Gergely Nagy analyzed how songs about Beren and Lúthien increase the dimension of scenes like Sam's fight with Shelob. These invocations link current events to the First Age hero Túrin Turambar and reinforce connections to evil figures like Morgoth.
J. R. R. Tolkien intentionally did not edit away the contradiction because he valued the sound of untranslated language and believed it added authenticity. Scholars note that such contradictions give readers the impression of real and complex history rather than a wholly consistent fictional story.
Ursula K. Le Guin made use of pseudo-references in her Earthsea novels while J. K. Rowling applied all four factors involved to Harry Potter and the Prisoner of Azkaban. Tom Shippey wrote that depth is the one literary quality distinguishing J. R. R. Tolkien from his many imitators who followed this technique.