In Ancient Egypt, there was a concept of purifying the dead. They put their mummies in the coffins along with some food and precious treasure. This showed the status of the person. The richer the dead person, the more will be treasure in the coffin. They believed the mummy to be resting in peace and that they would be purified with the provision of edibles and treasures.
Because kitty cats took over the world
So nobody had to look at the ugly thing
E G Y T I A N S B you R Y T H E I R M you M M I E S I N A C O F F I N B E C A you S E
To protect the bodies of the royal families from destruction of the elements.
So they may get to the afterlife