Also lol
As crazy as Isayama was
He didnt kill anyone in the main trio unlike gege lol
Tbf everyone in the main 3 were super important characters.
Armin was the Brain, Mikasa was the Ackermann killing machine & Eren was the MC.
Meanwhile, Nobara was always an "extra" character, in retrospect she was purely added for Yuji & the readers to grow attached to & then for Yuji's plot growth in Shibuya when she dies & he becomes a "cog" whose role is purely to exorcise Curses.
The people Sukuna massacred in Shibuya were important but not as important of Yuji being overconfidant & letting one of his most closest friends die.
Megumi, Yuji & Sukuna was literally chapter 1.
Ultimately Nobara was just a plot device sacrificed for Yuji, Maki became the Female MC right after.
Also Isayama literally had a Titan eat Eren and Eren "die" the very first time he fought a Titan lol. Isayama is a crazy writer, indeed.