I mean, they don't have to be dead or spirited away, they just don't have to appear in the panels. A classroom can be full, just put the MC in the back corner and only show her face.
He really messed up by not cleaning after himself, but it is very unique for the MC to actually investigate the exact process of his reincarnation. It isn't my first time reading a manga about a magician that reincarnated himself, but it is the first time I see them actually use that magic...
This was so cool. It makes total sense though, since in the first place he was a human who simply gained enlightenment, so he's even less of a god than Heracles
After Zeus jumped in on the second round I thought maybe Buddha will be the final boss, but not it isn't the case. That leaves only Odin as the only potential big hitter, since all the other gods left are kind of lesser even in their respective mythologies.
He isn't known as the strongest for nothing. If him being so weak was unexpected, then why did she even expect to be able to kill him in the first place? It will be nice to see him fight unrestrainedly for once.