Well, I thought it was about time I leave my current thoughts on the finale.
This isn't the type of ending I would have imagined at the start, but this series, this ending included, has an enormous amount of meaning packed into it and delivered upon what the series always said it was: Intentionally like ours, the world of Attack on Titan was
cruel yet beautiful.
After Eren's painfully understandable yet monstrous actions, the people and world we've been following throughout the story did not go on to be perfect and flawless, but they did go on and people could live lives full of the meaning.
That said,
I understand why some people are upset with the ending and I think it is in fact due to a flaw of Attack on Titan's ending: Hajime Isayama went to great pains and lengths to establish the nature of the world or, rather, the psychological nature of the people that live in the world and did so masterfully, but the lack of a proper hero to root for or an emphasis on any one particular journey meant readers and viewers are bound to feel less grounded in a world, less willing to stay
in it, and less likely to feel with said characters.
Isayama turned the hero's journey on its head beautifully and the story is more rich than the vast majority of most hero stories, however, the hero's journey has been beloved and prominent throughout human history because a person is more like a hero on a journey than a world that contains many great journeys. A love story is similar in that the journey is to find and manage love, similar case goes for a "coming of age" stories, and many others; goals are built from the start and clear. So, while not focusing heavily on a typical, cliche "quest" can lead to a lot of meaningful storytelling, it does make it harder for readers to feel empathy and satisfaction in the story. If the typical hero story beats were paid more mind in SnK, then as
@desin24 pointed out with his Naruto example, the readers and viewers would feel satisfied as they can see a hero or heroes have their clearly defined start, build up, and end goals get achieved accompanied by more satisfaction.
AoT flipped the goal to be achieved on its head and didn't reestablish what the end of the journey should actually look like: It's hard for a hype train to easily pull into the station when it's hard to tell if the train's on a track at all, even if its actually been on the same track for some time.
Still, many of the remaining main characters were shown to have returned to or found some sort of happiness and/or meaning, even if the source of happiness they're returning to obsessing over an old, hopeless crush.
The explosive growth and technological development implying successful negotiations, trade between the nations, and multiple generations of life.
Still, our world and theirs are inherently cyclical due to human behavior and there is no one everlasting, perfect solution. This is a message that the series has been trying to hammer home since the plot first hammered Eren's home, before that even. If things can't go wrong, then there would be little meaning found in them going right. The meaning-filled life Armin spoke of and lived would not have been possible if it weren't also possible for things to eventually go wrong and for unfair deaths and destruction to occur like we saw at the end of this final chapter.
Still, this is a situation that Isayama has been trying to get us to understand that it will keep happening, even if a world absent of titans, with titans, if Eren and Ymir never did the rumbling, and even if Eren and Ymir succeeded with the rumbling. The series has also made sure to make note of what should happen with the boy and the world tree seen at the end:
( The following manga pages are all sourced from
https://ww7.readsnk.com/ and the quote is from
here. )
"Why did things end up this way?
Having your mind and body rot away,
Having your freedom taken away,
Losing your sense of self...
Anyone who knew they'd end up this way
Would never step foot on a battlefield
But something pushes them onward.
And they all walk into hell anyway.
Usually that something isn't their own will.
The conditions and people around
them leave them with no choice.
But people who push themselves onward see a different sort of hell.
They're looking at something past that hell.
It might be hope,
Or it might be yet another hell.
Only the people
Who keep moving forward
Can know for sure."
- Eren Yeager / Hajime Isayama, Shingeki no Kyojin.