Dude, do you really wanna have a nigga moment over anime? I'm not even sure if you're a native English speaker with how you word things so I don't wanna bully you but I saw Kiritsugu as jaded because he took on an extremely cold worldview due to bad experiences and even his relationship with his wife was fucked up since he'd fuck Maya on the side knowing he'd need to basically kill his wife to eventually get the holy grail (if I'm remembering that correctly), maybe you just view the word jaded differently than I do but he was definitely a tortured soul even if he had ideals that he didn't fall away from. I think that growing up comes with decisions you've made that you aren't happy with even if you think you're in the right which kind of embodies Kiritsugu's entire character, that is a lot more appealing to me than anime Shirou who seems a lot more simple and to the point, he was a basic high schooler with a mostly normal life and he sticks with his ideals no matter what anyone tells him. On it's own, that's a basic Shonen protagonist but when contrasted with Archer trying to blackpill him, it comes off as more profound and in the VN it probably really was by a lot more.
I don't really disagree with the rest of your analysis very much but if we're talking about anime vs anime then a lot of the depth about Shirou you're conveying just was not done very well in the UBW anime. I enjoyed the ideological conflict between Shirou and Archer in the anime, it's one of the very few things I found interesting and the reason why I'm still open to reading the VN, the idea was really cool but there wasn't very much meat on the bone when it came to the anime.
I actually feel bad about saying he's so shit now that I know about the dad shit, I think the only role I liked him in was Masaomi Kida from Durarara. I guess I can't 100% blame him since he just tries out for shit, the directors who cast him as serious roles he doesn't fit deserve to be criticized more but you don't see them while you hear this fucking dude everywhere so it's easier to just take out your frustration on him. Dude really does not fit as protags tho, I remember being annoyed with a lot of Todd Habberkorn's casting too and then once I heard him in more comedic roles, I didn't think he was a bad voice actor anymore, I just thought he got miscast as more serious characters too much.
I am not native english speaker (thank god).
"he took on an extremely cold worldview due to bad experiences"
And this is where you got him totally wrong, jesus fucking christ. He was never like that because of his past experiences, holy shit, pay attention to the whole backstory episode. he killed Noritaka when his whole life was alright, he did it because of his ideals, not because of trauma or shit like that, he punished the bad man even if it was his father. And another example of how bad Fate/zero anime is the omission in adaptation of Maiya's background with him rescuing her but they couldn't get her rape baby (who would become an important character in another series).
Or even that he thought about dropping everything else before the war to leave with Irisviel and Illya but had to put back into it because of Irisviel? All these things that were included in the other adaptations (zero anime is literally the worst of all adaptations), that paints Kiritsugu as a weak willed man that the anime gloss over it.
"I think that growing up comes with decisions you've made that you aren't happy with even if you think you're in the right which kind of embodies Kiritsugu's entire character"
and this is how kerry went about it: I will use this supposed super wishing machine to get world peace.
Do you understand how silly it is? Do you understand that other people wanted to reach the root and kerry wanted to use it as a magical way to rewrite the world like it would be so easy? Don't you get how fantastical it sounds and how everyone in the series never went got the same type of wish?
Then you have Shirou, who went a such traumatic event that even if he had the possibility of getting his life before back, he never even once thought about it. He is selfless after the great fire. He will do everything he can to save others, and this way of life you can see in the anime and even more in the VN. He is in the holy grail war to not let other people get their desires rather than to desire something for himself, even if it was the easier path.
He is literally a machine at this point, every thing he does is mechanically, he does so well in archery because it is a mechanical act, he never does because he enjoys it or likes it. It is just a path for him to become better as a magus. Even in the anime original ending, he left the clock tower ambient who would help him with his path as a magus to go solo helping people. In the last shot of the anime you have this scene where he is in the desert, but his skin and hair are still orange, showing how he will go to a similar path as Archer but it won't be the same, even if their end will be surely death.
The main difference between them is how strong his will towards their desire (the same) is, even if Shirou's ideal is not born out of him like with kerry, it is a borrowed idea, he will persevere to reach it by his own hands.
And yeah, the anime doesn't get the full picture, but that is alright, since the whole of shirou can just be fully understood by reading the VN, the anime doesn't get into his mindscape and we get to see how he see things. You don't get to know all characters in the series by watching an adaptation of a single route, you did not even watch the first anime, with the whole introduction to the setting + the pure version of his ideals to see how Archer vs Shirou is the personification of ideals x reality.
Or even that I bet you don't know that FGO exists, and an EMIYA version of Kiritsugu exists. And even in this setting, his character is still way weaker than both Shirou, Archer in any incarnations of them
Or even what truly jaded means for someone like Shirou.
While on the subject on stay night has anyone tried out the manga adaptations of the routes?
I saw an add for the new UBW one recently and wondered if they were more faithful to the VN then the anime while not having to sink in almost a hundred hours to play them.
I did read all of them (the first one from 2006) twice. All of them are better than the anime, since from the beginning, all manga adaptations of Type-moon have been better than their anime adaptations.
The first FSN manga isn't fully translated into english but it is one of my favorites since it is basically a fusion of the fate route, with the middle of UBW and bits of Heavens feel. So in terms of adaptation, it is basically a frankentein one but I still enjoys it a lot rather than the normal fate route. The artyle change a lot as it goes too, the characters start kinda generic, but eventually become way more stiffer and bulkier
The heaven's feel manga has a way better art and it is adapted by Task Onna who is a fan, it helps a lot, he went into adapting parts of the original VN rather than the realta nua version, so there are lots of sex scenes like the original.
the UBW one is adaptated by Daisuke Moriyama, which is also a pretty stabilished mangaka already and it is really in the beginning (1 volume out already). But he already changed some things already (at this point, I think it is fine, to see little differences between the original and these versions).
It will take literally years to see the stories completed by this means, so if you want the fully story, go read the VN, since it will be easier