Boromir is a walking example of Elrond’s insistence that ‘men are weak.’ He’s brash, impulsive and doesn’t appear to truly respect the corrupting nature of The One Ring. Instead he seems to serve no other purpose than to hinder the quest and convince Frodo with a visceral example of man’s weakness in the presence of the one ring.
Or is he? Upon more careful viewings (and possession of the Extended Editions) Boromir’s motivations and morality look a lot more sympathetic. Even downright noble.
When we first meet him, Boromir is representing Gondor at Elrond’s council to discuss the fate of the ring. There, he is quick to cast doubt on the idea that the ring can be secretely destroyed in Mordor (becoming an internet meme in the process) and why wouldn’t he? Boromir comes from a city habitually at war with Mordor and knows firsthand the defenses it has in store for our heroes. The rest of the council has lofty ideas of success, but few of them have any actual experience with Sauron's region. Boromir brings up a legitimate concern, that should this proposed quest fail, they will have given the enemy back his ultimate weapon. Most of those on the council seem to scoff at Boromir's bluster (he’s not a skilled diplomat, that’s for sure) but ultimately it’s Gondor’s men that have been fighting, and dying, to keep Mordor from spilling over into the world of Middle Earth. The council should respect his opinion and his city’s contributions at the very least.
Throughout the rest of the quest, Boromir has an uneasy relationship with Aragorn. He’s initially standoffish as he learns Aragorn is the lost heir, and things don’t get much better the more he hears about Aragorn’s views of men (humanity sucks!). But consider how crushing that must be for Boromir; Elves, Dwarves and stern wizards named Gandalf like to constantly remind men how weak they are while offering no real assistance to Gondor, whose town of Osgiliath remains in a constant state of ‘under siege’ or ‘about to be under siege’. Now this long lost heir to the throne has come back on the scene, but he shirks his responsibilities while agreeing with everyone else about how weak men are. Boromir has probably dreamed of Aragorn’s return and is devastated to be reminded that even humanity’s savior wants nothing to do with the race of men.
“Have you so little faith in your own people? Yes there is weakness, there is frailty, but there is courage also, and honor to be found in men! But you will not see that.”
Boromir goes on to proclaim that Aragorn is afraid of who he is to which Aragorn responds,
“I will not lead the ring within a hundred leagues of your city.”
That exchange is a gut punch, and it shows that Aragorn’s worldview, while coming from a place of humility and intelligent caution, can feel callous and downright mean to his fellow man. The use of “your city” must be especially hard to hear for someone who has spent his life protecting Aragorn’s throne. For those interested, the full scene can be viewed below.
A scene from the Extended Edition of The Two Towers further elaborates on Boromir’s motivations; we see he originally didn’t want the ring at all. When Denethor tells Boromir the ring is in Rivendell and instructs him to bring it back, Boromir’s first words are that the ring corrupts everyone. It’s Denethor, acting in line with years and years of favoritism, who tells Boromir that lesser men are corruptible, not him. This family pressure combined with a burning desire to save his people was an obstacle other members of the Fellowship didn’t have to deal with. Not only that, but in this scene we generally see Boromir being a strong leader whose revered by his men; he’s just led Gondor to victory, he’s bringing out ale for his men, and he’s sticking up for Faramir after another of his father’s tirades. Scenes like this paint a much different picture of his character and motivations.