wrong your connecting a concept of afterlife with morality they are vastly diffrent. Also digging a hole and putting a corpse in it with our with out a to go bag has nothing to do with morals and every thing to do with sanatation

you are correct about natural instinct though. we would have needed moral concepts to work as a group, which by the way we working togther long before we buried our dead. The concepts of afterlife and worship would most likely have come into being after morals, although you could argue that we, as a species, had not defined what morals were.