Nature of Death
Different species and societies believe a lot of things about what happens when the sentient creatures of this world die, but this is the real deal. The truth of this matter is knowable by those who command the power of magic, and most societies have gleaned at least some of it, and so you will see some commonalities around funerary customs because of it.
Living beings have souls. Beings we would recognise as intelligent definitely have souls, and lot of beings we might not see as intelligent have souls, too, actually.
Terminology for this move is be English, with culture-specific terms as something for later moves. "Soul" refers to that spiritual essence of a being that persists after death. It is capable of thinking, feeling, and wanting things independent of a living body, and it has some limited ability to communicate and impact the world independent of a living body, especially when interacting with certain magical beings or if it had magical power itself in life. When a being with a soul dies, the soul becomes a "ghost." The ghost remains in this world. Remaining in this world causes it pain. It longs at a deep level to leave. It can only leave through special places which it can perceive like glowing cracks in the world. These are "rifts." The nature of the rift and what if anything lies beyond it is outside has not been specified. The ghost doesn't know, it just knows it longs to pass through. It sees the rift as somehow beautiful and holy, and living beings that can perceive rifts also feel a sense of sanctity around them. Many have deduced something of their relationship to the dead.
The dead may long to pass over, and they feel pain by remaining in the world, but if they have powerful attachments to the world for some reason that they struggle to let go of, they can linger for quite a while. Nothing is forcing them to leave. Therefore, this world is haunted, especially by the recently dead.
The rifts have fixed locations which form places that even the unsensed can feel as sacred or powerful somehow. It is common for religions to place their holy places there. It is also not uncommon for this to become a form of religious extortion, because a religion can control all the places in the area where the dead can cross over and control the access of the dead to those places. A temple can be enchanted to prevent a ghost from entering without some part of their corpse, and a temple funeral can be key to peacefully passing over - it can also imprison a ghost in the temple until it passes over.
Knowledge and control of the rifts let a society both serve and manage the dead, and the living. A person and their family could be punished by killing them and not permitting the rituals that give their ghost access to the sacred places of their people to cross over. The ghost could try leaving the territory controlled by the religion to find a free rift, but they probably believed in life that they had to cross over in a temple to be saved. If the society is enlightened enough to leave some rifts for animal souls to cross over, then the criminals could use them, too, but they might be too attached to their living beliefs to accept that humiliation...
