You're not wrong about MC being overconfident, though he has a reason for it. It's been over a dozen floors since he's had to "go all out" and feel the sense of mortal danger. Even in the floors where he needed multiple rounds/resets to beat, he wasn't really in mortal danger in them. Not like he was in the first handful like when he fought Itty.

He's wanting to see what he's capable of which is why he's even wanting to fight the demon king without the sword. He wants to see what his limits are so he can improve on them and get stronger.

Seems like Pope is the reason MC and his lover was seperated when MC arrived to this world after they both died. Because he said it was a mistake to seperate them. This means, at some point MC and his lover wasn't seperated, which means the Pope probably did whatever he did before in the past, which is proven when he said rewrite once more. Pope has probably "rewritten" the world more than just these 2 times. Not sure what his end goal is exactly but his power also seems similar to MC's with the whole book angle to it.

Makes me think Pope may be an otherworlder from earth too and was an author like MC potentially.