The way Gaara's story was written he only killed those who attacked him, (this included Lee who managed to make him bleed, in his mind that made him worthy sacrific.) he had been weaponised, and that had backfired on the village completely. You can't really blame a tool for carrying out it's purpose. So I don't think you can say Gaara couldn't be redeemed, he was a tool first, when he stopped thinking like a tool, he proved his loyalty, he sacrificed himself to save his village.
The thing about this manga is, that the less you have killed the more redeemable you are, the biggest villains in the manga Obito and Madara were both redeemed at the end, I still don't understand Madara's redemption, neither deserved redemption but got it, in love story that mirrored Naruto's was considered worthy of coming true where NAruto's wasn't apparently for a guy you can only prove your love if you try to destroy the world, Trying to save the world just shows you don't care.
The only enemy that Naruto was not shown to care to redeem was Kaguya, Everyone else he symphasised for some reason, but Kaguya he never cared to understand how she fell from grace. Which I always found odd, the final enemy and we never found out her motivation, but then again the whole Kaguya thing was a mess, I can't help but feel the only reason she came into being was because Kishi was sold the idea of the last movie and he introduced a mother so the sage could have a brother who had a a clan of his own that was not on this planet for some reason. He failed misarably, Kaguya has to be the worst final boss I've ever read, and noone cared for the movie villain because it was done so badly. (I can't beleive the voice of Lalouch was wasted on this sh*tty enemy.). Kaguya looked like a tacked on enemy that didn't fit in with the story at all.
I agree.
You know "redemption equal death" trope.
Well, nagato do rain of castamere to Hanzo. And then redeem and dead.
Obito do something similiar, redeem and dead.
I don't consider madara get redemption.
Zabuza get redemption because he realize he's gay and dead.
Garra get redemption and part he was dead and revive.
The only character who doesn't die while get redemption is kabuto.
Naruto doesn't care with kakuzu either. That's why he doesn't tnj him.