While I personally think the acting was also not as good as it could've been, my wife actually got fooled into thinking it was real, so it seems to work for those who aren't expecting any subversion to happen.
I think it was pretty obvious that the monsters there are super strong because even after he leveled up, he couldn't even scratch the skin/hide of a dead monster. Even after all that leveling, he could only beat them through his status effect skills. He didn't suddenly start beating them with speed, strength, agility, or weapons.
To add, he isn't alone. He had that uncle and auntie who cared for him after he escaped abuse.