LotR Gave Us a Lesson on Heroism Superhero Movies Failed to Learn
And what is that lesson, you might ask?
Well, the superhero movies implicitly or even explicitly accept the definition of heroism as "deeds of an exceptional individual". It is baked into the genre. That's where the "super" part in superhero comes from, after all.
Sure, there is teamwork whenever the superheroes get put together in a team movie, and occasional nods to the notion that anyone can become a superhero if he works hard enough – though despite all the plot contrivances invented for the sake of giving them something to do, characters like Hawkeye or Black Widow tend to be largely useless next to the rest of the Avengers' lineup, once action starts for real.
But even in case of characters like them, those without explicit superpowers, heroism is still tied to exceptional personal fighting prowess.
The Lord of the Rings, however, does not depict heroism as something that comes from one exceptional individual, and is measured in large part by fighting ability – in fact, the character of Boromir, who believes in this idea, is used to criticize it.
What saves the world is a fabric gradually woven from interconnected acts of kindness, bravery and fortitude, of refusal to accept moral compromises, and of the friendships that people build among their trials. No single person could conceivably destroy the One Ring.
Even Frodo, with his exceptional moral fortitude was at first physically almost incapacitated (in the movies it is less obvious, but the book makes it much clearer that by the time of stepping into Mordor his existence is a waking nightmare, allowing him almost no rest for weeks, on top of "normal" difficulties of traversing a blasted desert with scant foot and water) and then, finally, mentally broken by its corruption.
But his bonds with other members of the Fellowship, his kindness even to his enemy, Gollum, and his ability to accept help, helped him when even his lack of ambition to be a hero was not sufficient to resist the pressure of the Ring.
That theme repeated itself several times with other characters as well, when mutual trust, friendship, relatively small acts of kindness or relatively large acts of doing the right thing despite the odds, allowed to reach a good outcome, which would have been impossible to achieve with sheer prowess.