I deeply believe in this at least.
I believe that most if not all ancient shamanic cultures, specially native americans, used different plans, mushrooms and substances found in nature to alter their consciousness, connect to nature and to the Divine, communicate with spirits, and also for spiritual and mental healing purposes.
Most indigenous cultures claim to have communicated with Earth, with the trees and the plants, with animal spirits and the Divine.
For example: In most Latin America and in many different parts of the world, people are giving and attending to Yagé ceremonies (Ayahuasca). This indigenous ritual has become very popular these days. However, what is curious about this is that native indigenous claim that "the trees in the Amazon told them which plants and substances to combine in order to make the magic and healing brew". Native indigenous also had deep knowledge about plants properties, specially for healing. Many cultures claim that they got their knowledge straight from Nature.
These kinds of perceptions and knowledge suggest to me that they had been under altered states of consciousness / trance on several occasions in order to perceive in this state and level of depth.
We know they were friends with the Nature and used to know it well. I believe they got their psychedelic substances straight from Nature and developed their spiritual insight and culture based on such experiences.
Nature is full of medicine of different kinds. Both psychedelic / psychoactive and non psychoactive. We have explored these substances too little and ignore that for instance, there are plans which were used for astral travel, for divination, for healing and also plants which take you effortlessly to other dimensions and realms. Nature is full of mysticism and magic in my opinion and I believe that ancient cultures were well aware of this.
I believe that psychedelic substances have had and still have a great impact in human consciousness evolution and they have triggered it through our history.
Of course, take everything with skepticism and make your own conclusions. I may be wrong of course: But this is something that I deeply resonate with, and deeply believe in, which I wanted to share.