Excellent chapter, love how it intertwines the fantastical elements of the story with a reflection on how we affect and are affected by others.
The incubus are born from those who die with malice and hatred in their heart. Then they feed on people's fear while tormenting them with nightmares, symbolizing how past traumas can haunt and perpetuate fear and anxiety. The incubus also convey the cyclical nature of being hurt and hurting others. This is illustrated by how the incubus are born from corposes and lead to more death.
The next scene deals with demons and corpses. Here we're dealing with a broader range of negative feelings, and how these can overtake or consume a person. The corpses are those who have become dehumanized by their own inner demons. This moral corruption is morbidly highlighted when the daughter kills her father which, of course, was a result of Guts involving them. Our own struggles can have a devastating effect on others, after all. Guts' coldness led the daughter to her death which, in turn, resulted in her fathers. Yet, Guts' coldness, too, has been shaped by the actions of others.
This is the world Guts lives in. Yet it's a world that everyone inhabits, but facing it head-on reveals the harsh realities within yourself and humanity.