What is a "monster"? - Dungeon Meshi Fanfiction

- Cover is currently a picture from pinterest, until I draw something fit for it, let it be-
AN: This whole thing is heavily influenced by my mindset and morality, whoever has a problem with any aspect of it, please be respectful, I understand that everyone has different beliefs.
It will be cringe, it will be old-school fanfiction, I don't care. It's my work and I'm doing whatever I want, deal with it.
Or leave.
Up to you <3
- I do not own Delicious in Dungeon by Ryoko Kui, this story is purely and respectfully based on their work -
"One incident, 18 different claw marks over three meters apart against the wooden floor. Something that caused that massacre is still roaming this world, I want to see that creature - Come on, Laios, we aren't ever going to find it, six years already passed since it happened, it's propably already dead."
Laios, Marcille and Chilchuck went back down the dungeon, along the way Senshi joined them, they fought and ate the dungeon monsters, all for the sake of killing the Red Dragon and saving Falin. That was the main goal, but of course everybody had their little side goals. Unnerving fact of something causing such a saughter at seemingly innocent house being still alive was creeping at the back of their minds, nobody actually hoped to encounter it, especially after hearing gruesome details of that scene.
Until they did encounter it. Or it actually found them. And it revealed the other part of the story nobody even wanted to think of.
When ends a human, when begins an animal and where do we draw the line between innocent and monstrous? When do we can say that we have gone too far? Is death good or bad?
"It depends" we say, but on what?
(Oh how I love topics like that)