I think it’s connected to how Tolkien always connects his ‘fantastical’ elements with the ‘ancient’.
The balrog is a primal evil the dwarves released by digging too deep; Tom Bombadil has been alive forever; Fangorn and Mirkwood forest are remnants of the ancient forest that once covered the world; Gollum has been granted long life by the ring making him a remnant of the past that has survived; The elves’ long lives make them a living connection to the past.
His mythology is all about people touching and being touched by something primally ancient, so to confront that world requires that kind journey through time.
I wouldn’t claim any special insight. Like a lot of people I read LotR at a very formative age and as a result I have a lot of thoughts and feelings about it.
The balrog is a primal evil the dwarves released by digging too deep; Tom Bombadil has been alive forever; Fangorn and Mirkwood forest are remnants of the ancient forest that once covered the world; Gollum has been granted long life by the ring making him a remnant of the past that has survived; The elves’ long lives make them a living connection to the past.
His mythology is all about people touching and being touched by something primally ancient, so to confront that world requires that kind journey through time.