Final Fantasy X always shows the story from the view of Tidus, in the pursuit of his father and how he meets new friends and allies on his quest. There are even some lines of dialogue that say that "this is his story", when Yuna is clearly the more important to the plot. But it becomes more and more obvious, over the course of the game, that he's just extremely self-centered and doesn't pay much attention to what happens to other people. One the one hand, his complete ignorance and disrespect of all tradition may have been what ultimately ended the eternal circle of Sin's death and rebirth. But at the same time he doesn't get any of the numerous hints that summoners have to sacrifice themselves to defeat Sin, even though the player should have it seen it miles before it's said explicitly for the first time. The only help he ever provides for Sin's defeat is encouraging the other characters to doubt what has been portrayed as the truth for a thousand years, if only by being extremely impulsive and ignoring all orders. For most of the game, he just tags along with the group and causes trouble.

As Jecht himself had done during the last pilgrimage, Tidus matures a great deal for the most part during the story. Also, not knowing about customs, rules, traditions and such like Jecht didn't, how can it reasonably be held against Tidus for making trouble despite not knowing the rules? To blame him for seeing a lie in the Yevon after the wedding scene and trying to rebel against it when the others clearly saw it and still tried to finish the pilgrimage is really cruel. Furthermore, the player can see the twist coming, Tidus does not and reasonably cannot because nobody ever once explicitly tells the man what's going to happen at journey's end, choosing to stay silent and let him blabber like an idiot. I don't think he's stupid for speaking about things he doesn't know about if nobody tells him anything. Thirdly, while true that he does come off as self-centered and whiny, he does make good points. What would've been the purpose of her dying if the cycle continued anyway as Auron knew it would? An important final thing to notice at near game's end when Yuna tells Tidus that "it's my story too!" which means that while Tidus may be telling us that it's his story, any other character like Lulu or Wakka can tell us "This is my story..." and provide their own monologues if we heard this game played out from their perspectives. Finally, that only help you just listed makes for quite a big step considering that Yevon's teachings was all that the people ever knew up until that point.

Tidus being such an arrogant, unlikeable figure that he's nothing but a Creator's Pet and came close to simply being a Designated Hero. He continually bragged about his Blitzball ability, very childishly made a scene with a megaphone in Luca and stole a complete stranger's binoculars on the S.S. Liki after pointlessly climbing all over him. The game was also notorious for changing its mythology to lessen Tidus' misdemeanors; early on, it was clear that Tidus could hurt Yuna if he interrupted her communication with the Fayth in each temple. Later on, Tidus had no issues with trying to pry open the door to the Chamber Of The Fayth, remarking (impolitely) "you can stuff your taboos". Yet nobody pointed out his arrogance or told him to grow up. Instead, like the majority of generically-attractive male teenage characters in Japanese games, his misdemeanors are immediately forgiven or ignored altogether, so the other characters can all get on with praising him, with Yuna bending over backwards to make him a guardian after just meeting him, Lulu saying he was possibly the greatest guardian who ever lived while Auron — who had actually defeated Sin — was standing ten feet away and so forth.

He was having childish fun at journey's beginning and really had no idea about what his journey was going to be like. Blaming Tidus for being immature at the start of the journey is harsh (though understandable given his age, not like his father was any better). Tidus was still immature at that point in the adventure (as we see from his first view with the binoculars) and it's not uncommon for a sports superstar to brag about his trade, especially in such a Crapsack World such as Spira. However, the portion where he told everyone to stuff their taboos was risky, he had every right to say it to them. He only told them to stuff their taboos after 1: The Guado's merciless attack against the Al Bhed. 2: Operation Mi'hen, which was really a political ploy to enhance Yevon love against Al Bhed to further tighten their grip on Spira. 3: Seymour's attempted murder against the party and 4: Yevon opening fire against the party with machina that are explicity forbidden by their own teachings. Tidus did show that he was trying to learn their ways, but once he and the player increasingly saw that Yevon was full of it, he reasonably (though hastily) believed that the fayth bit was a lie as well. Nobody else stopped him, so they probably started thinking outside of Yevon's box. This was evidenced in an optional area where the player can revisit the fayth with no risk of harm. His misdemeanors can also be forgiven if only due to his new person/Sin's Toxin victim status. Finally, Auron didn't defeat Sin, Braska did. However, that came at a price that we (the player and Tidus) learn about as Yunalesca tells the truth behind the final summoning. Lulu praised Tidus because Tidus's new way was the closest to an alternative method anybody's ever tried at vanquishing the beast, and proving that the Beast could be beaten without senseless sacrifices or the teachings of Yevon, which is more than Auron accomplished during his stint as Braska's Guardian.

There's one scene in particular that shows how Tidus really matured and was both a Crowning Moment of Awesome and a sign of Tidus being Badass. Right before the party goes to talk with Yunalesca, Tidus is begging Yuna and the others to find another way to stop Sin and they say no. Tidus then gets called out for being childish and selfish by members of the party. He throws it right back in their faces by pulling out a "The Reason You Suck" Speech crossed with Adults Are Useless and Whatthe Hell Hero by saying he'd rather be childish then be like the adults of Spira who are a little bit too willing to sacrifice and die needlessly for a brief peace when they haven't taken the time to sit down and think of another way to permanently end the suffering in Spira. That moment just made my finding Tidus likable just skyrocket to admiration when the only answer the party gives is "It's the only way." They just proved him right with that one sentence.