The Lord of the Rings represents an archtype of the battle of good and evil, writ large, yet with small fry—diminutive, relatively helpless creatures called hobbits—as the central actors.
All of the powerful forces aligned against one another, many of whom are all but immortal—elves and walking, talking trees (ents) for example—in the end depend on these apparently insignificant players to provide the critical fulcrums on which all the events are leveraged. Even wizards have to rely on them to execute the most important tasks... and although there are a lot of other, perhaps technically more capable, players eager to assume that role, in the end most of them have some deep and vital flaw, always related to vanity and ego, that disqualifies them
In some cases their vain ambitions end up serving positively in some other way... but never when it comes to the ring, which can't be touched by any but the purest, simplest soul. Anyone with aspirations to power is ruined by it—and even hobbits are not immune to its charms, because sin (the ring is, in its essence, the original sin)—corrupts everything it touches. The ring ultimately devours the soul of anyone who falls under its spell.
Hobbits live a decidedly pastoral life, emphasizing the role of farming as a primary civilizing factor in the world. It establishes a populist base for the action. The various nobilities that struggle in an epically Tolstoyan manner, each of whom seems themselves as "the" major player in the conflict (the dwarves, the elves, the ents, the goblins, etc: all have what they perceive as some major piece moving on the chessboard) are all actually revolving around the hobbits; but no one really sees this except Gandalf, who plays the role of the saint, the one who has insight: although even his insight is not infallible.
A fallen angel orchestrates the conflict: Saurumon, who waxes under the spell of the devil (Sauron.) At the time the story of the hobbit opens, the conflict is already an ancient one. The premise is that evil is vested in a materiality (the rings) and that the one who controls this materiality will gain power over everything. The rings are, in other words, talismans representing a great power, but it's a power of corruption; and that power is in abstract the immanent world, the world of things. This world of things is, by and large, a world of glittering treasures (whether gold, or kingdoms) all of which turn powerful engines of desire in the various characters.
It is a world of attachments: and the singular voyage of detachment that progresses throughout the trilogy (throughout the plot, everyone else is doggedly pursing their attachments) is Frodo's selfless quest to destroy the ring, which carries him through all the worldly fields of action pursued by a golem (Gollum), effectively his own personal demon—whom he has, surprisingly, a complex and touching sympathy for. This is a sophisticated mechanism, indeed, and Jackson did a masterful job of rendering this rather impossible character in the movie, not just as regards CGI, but also his schizoid, bipolar persona. Frodo is also accompanied by his good alter ego, Sam, who remains loyal; even when he is rejected by Frodo's frustrating acceptance of Gollum.
The hobbits represent the ordinary within this world, which is essentially not corrupt: and it is their apparent insignificance, the fact that they can be so easily overlooked and discounted, that becomes the weapon that defeats evil in the end. In this sense, it is a story of everyman against forces much larger than himself: again, a form of populism, but a populist movement against evil on a monstrous scale.