Fantasy, Action, Adventure
Let's be real: Tolkien basically invented what we consider to be modern fantasy.
Sure, of fantastical creatures and magical powers are nothing new. And the sort of mythos invoked by the genre has been around presumably since prehistory, and has survived in most cultures through countless tales in oral tradition or epic poems.
But good ol' J.R.R. is the grandpappy of fantasy as we know it.
Before Tolkien, when you heard of elves you'd think of some Keebler-like creatures: really small people with pointy ears who lived in trees or provided slave labor at the North Pole. Dwarves were the friendly little guys helping out Snow White; and hobbits were theoretical homo sapiens precursors.
Tolkien created a high-fantasy canon which is so beloved it's has been copied over and over again by writers through the past decades. Nowadays this Tolkien-based universe is one of the first things people think of when they hear "fantasy."
If you read The Fellowship of the Ring, action probably isn't the first (or tenth) word you'd use to describe the arduous journey through thousands of pages of landscape description and elven poetry.
But this isn't the creative musings of a philologist—it's Hollywood, baby, and people want action. When the book was on the chopping block, none of the intense battle scenes were cut and, given the visual nature of combat, these scenes in the movie take up a comparatively long stretch of time compared to their written counterparts.
After all, what's a fantasy movie—with medieval armor and weaponry and evil creatures and frightening beasts—without any action? That's like leaving the bacon out of a BLT; it's practically a misdemeanor. Save the vast histories of Middle-earth for the Silmarillion: we'll take are action sequences like the hobbits take breakfast.
Hot and heavy and all the time.
Probably more than anything, The Fellowship of the Rings is a story of adventure. No surprise there: adventure is at the heart of almost every fantasy narrative. Just like the reader or viewer escapes into and experiences a whole new world of wonder, the protagonists venture out into the world at large and are challenged to grow along the way.
And while the journey of a character doesn't have to be a geographical one, that is often the case in fantasy and holds true in The Fellowship of the Ring. Frodo's journey is both one of personal growth (from unadventurous hobbit who stays in The Shire to the bearer of the most dangerous burden the world's ever seen) and a physical one that takes him into the heart of the conflict of Middle-earth.