Anyways the plot is different from the typical going back in time story because MC actually going back into the past with his current body/memories and his younger self also exists at the same time and there's no time paradox because he can use his missing older brother's identity in a sense. I actually like that MC is not a perfect protagonist but he has his flaws. He was cynical and he's smart and yet he got comfortable with his life so he never anticipated the disaster and he was somewhat arrogant and brushed off concerns about the dungeon break which he later regrets. His main regret is with his adoptive father because he could never call him father and actually tell him how much he loved his dad because he was scared of vulnerability. I really like that even after time travel he can't ever be his dad's son again because he's now closer in age to dad and the past version of him is not his dad you know. His regrets regarding his dad and his close ones death keeps him willing to save the world even though he doesn't want to be a fighter and just love in peace.
I also really appreciate the interaction with his students. He is a strict teacher and he initially doesn't really care about the kids except their value in the future but he ends up actually being a good teacher and connecting with them.
Overall I think I like this story a lot.
