Pretty much. They keep digging and talking to the few primitive groups left.
Some animals that are smart and social have funeral rites. Crows and elephants. Been known to visit locations where the dead were, leave items for their poor dead friend. A dead human and a living human are basically the same except something seems missing. We know now it is the arrangement but to our ancestors it was some component. Well if something is missing it must be out there somewhere.
Funeral sites are built. People go there and look at the little stone. Maybe the thing that is missing is in the stone. Leave items and gradually question why they are doing it. It must be transactional. Offerings develop. I give this cup of wine and you help me with my crops this year. Ancestor worship is still common around the world and why should it not be? Your parents always looked after you and you are still helping them.
The ancestor worship grew. Some ancestors were more important than others. Great warlords are still revered for centuries. Eventually morphing into a small god who protects the tribe. The small god is better than the small god of the other tribe. There must be a god greater than them all.