4hrs was indeed ridiculous. If hunters were stronger than regular people then that'd be one thing, but they commented that he's essentially a civilian. All of this previous fights suggest the same as well - which makes 4hrs of running beyond what he's actually capable of.
As for going into the dungeon himself - I suppose he had the impression that you could always leave. If you assumed that, then dungeons would be considered safe. That said, he did just encounter a boss room that did not allow anyone to leave, so he indeed should have been more careful.
Overall he just seems to get overconfident, and his currently levelling up has done nothing to address that. He is eager to earn money to help his mum, so at least that's noble.
The biggest standout of this show is actually the art style where people are rather lanky, which gives it a more oldschool vibe. The contents of the show isn't exceptional though. It's pretty in line with all the other "MC has a special RPG skill" shows.