Even though we have comedic Kaworu in the manga I enjoy the original Kaworu over the him in the movies. Don’t get me wrong, I really enjoy how in 3.33 Kaworu tells Shinji that even though he’s made mistakes, dwelling on the past won’t help at all. He also adds on by saying that redemption isn’t out of the question either. You can’t do anything about the past, but you can do something about the future.
HOWEVER, it’s his character in the original series that I’m drawn to in regards to his sacrifice (and there’s more to his character, but again this about this part of his character).
1.) Utilitarianism
He assumes the utilitarian stance to sacrifice himself because that means saving humanity. He sacrifices reclaiming the world for angels in favor of humanity because he knows that the expungement of humanity would take place (utilitarianism is sacrificing the needs of the few in favor of needs of the many).
If you didn’t know, outside of Eva, I’m into utilitarianism as well as the positive and negative commentary in regards to that ethical stance (as well as other things that ring some “What defines a good action?” bells).
2.) I really think his character deviates from common “good person” tropes.
This really wouldn’t be out of the question. Eva does subvert plenty of ideas.
Him being the angel of free will, you’d expect him NOT to be a character aligned with good. You would likely expect him to be one of the neutrals (maybe True or Chaotic Neutral). Free will is aligned with someone doing as they please. This would ESPECIALLY go well with the Chaotic Neutral alignment as this would give the person the greatest chance to be autonomous (*Defiant Kaworu voice: I do what I want, Shinji-kun.* Just imagine, haha).
Even though he is a good character, like other characters in Evangelion he isn’t perfect. Personally, Kaworu believes that life and death hold no differentiation (to also justify why he doesn’t fight to live other than him making a sacrifice), which they do. The reason for Kaworu not being perfect being important is because there’s good characters who’s actions or ideas are always right. “That character is never wrong about anything because they have good beliefs. Ever.” Not him, though.
He may be a good person but he’s not perfect.