Terrible first chapter.
1. They need to visualize how terrible the rats are. Is it a monster even a baby can kill? Is it a beast only the toughest of warriors can defeat? Got your answer? Then show it to us, don't tell. The chapter was trying to create some sort of urgency without properly setting it up which makes it seem like noise. This is also not relevant to the story at all, if you remove the part about the rats suddenly attacking then would the story be affected? No? Then remove it, it's just noise and dampens the pacing.
2. Worldbuilding has all been told rather than shown. Is the church greedy? Show us church members being greedy. Is there a class divide between specialized jobs and villagers? Then show class discrimination.
3. All characters seem so paper thin. Even at the beginning of the story, it's not hard to create 3 dimensional characters. These are just boring self-inserts which make it even worst. The point of a self-insert is to more easily slide into the role of MC to dive into the world and interact with the other characters. This world shows zero potential by the end of the chapter and the other characters also have zero personality.
4. There is absolutely zero hook before inciting the conflict. The conflict isn't even brought up by the MC, the prince brought it to him. That is a passive character and the MC is something you want anything but passive. And as for the hook, at least explain the flaw of the world just beyond "greed and class discrimination" - which the first chapter didn't even show. No hooks = no readers.
5. The manga art is just so generic. It's not memorable at all. It seems like an amateur did it.