Of course psychedelics aren't sufficient to explain anything. These are complex phenomena that have multisided explanations. For one thing, there's a natural, universal form of psychedelics that would have inspired the imagination, namely dreaming (so no drugs were necessary).

And yes, protoscience would have played a role: we posited social spirits to be comfortable in the alien wilderness, tying our intelligence to our social instinct.

I'm just saying that religions arose from shamanic animism, and shamanism is famous for being psychedelic. We can always go back further, though, explaining the psychological basis of our ability to tell stories or to understand anything.