>>46159270None of those unanswered questions mean anything.
That thing is a primitive lifeform that used to live in real world Earth during the Cambrian "explosion" called Hallucigenia and has nothing to do with titans, being used to illustrate the passage of time while Armin and Zeke discuss the meaning of life and why things exist. Zeke simply believes animals are here to live, reproduce, and die, but Armin thinks there is more to it than that.
Yes, Eren saw this future too.
The father of Historia's child literally doesn't matter. All that matters is that she had a child.
Google "Ksaver."
He was brought up because Armin held up a leaf that he remembered from his childhood and it reminded Zeke of playing baseball with Ksaver.
The writing is bad. You have to accept this.
Isayama's original story manuscripts were leaked online and the editors made him change the story last minute. Google Kichirou/Kichiro Moto story leak. Both stories are stupid, but the original made slightly more sense.