I believe we were able to survive in ancient times by becoming visionaries, shamans, or any other sort of spirit talker.
Our delusions made the legends and myths we hear today.
We made predictions and we were either right or wrong and depending on that the community either shunned us for scaring them or praised us for coincidentally recognizing patterns in the world and making predictions that would then become true.
Imagine yourself unmedicated in the times of tribes.
You have a delusion of a tiger coming to attack, you put the tribe on high alert.
Thankfully a tiger comes close vicinity of the nesting grounds.
You are praised for seeing the threat beforehand and now we have a dead tiger and meat for a week.
What do you think