That ant boss may as well have been a statue. No danger, no excitement, and lots of standing around calmly taking about what to do. Combat is not this manga's strong point.
You mean the super-tanky
regenerating Boss who'd just swallowed several powerups she was digesting and capable of creating an army of offspring flooding the dungeon as soon as they left it alone to Report?
As it was they
barely had the firepower to deal with it..
Not every dungeon problem/Boss is about flashy Raid Boss area attack patterns and explodey stuff....
Even if that Queen Ant wasn't "dangerous" in and of herself, doesn't mean she wasn't a major headache.
And you're forgetting that
only the MC would be able to go full Sumo Punch Wrestling with her as he did..
No-one in the world is as strong as him.... Anyone else would pretty much have been turned into mince meat by those jaws...