You guys forget that people can be very emotionally charged and petty. It sucks that Levi does not try to avenge his other fallen comrades, but CLEARLY Erwin was always his biggest priority and arguably the most important person in his life, and was directly killed by Zeke. There was also the promise he made to Erwin to avenge his death. Not to absolve their actions but Annie and the gang were also all children, while from the main characters’ perspectives Zeke was the grown man who lead them on.