I always find it odd how in these isekai novels the other world lacks basic ideas which are actually ancient here in Earth's history. Soap has been a thing for millennia and people have always been creative with their cooking as long has human history can be known. They only lacked the resources most of the time. I often feel like the authors of these sorts of novels purposely have the other worlds lacking such technology just so the MC can look smart when they introduce it.
Also, I'm wondering why all this world's resources seem to come from labyrinths. Don't they have normal agriculture and animal husbandry? Must they get all their flour, sugar, meat, etc. from the dungeon? I know they can (and do) grow things in their garden.
Another thought, how do normal people change their class? It hasn't yet been explained. We only know that Roxanne was surprised that MC could change her class so easily.