I've often wondered the same thing regarding technology and visions. I occasionally see great complex machines on my journeys and I wonder if perhaps in the ancient world seekers once saw what we consider to be modern technology in their journeys.
I'm also prone to believe that these entities do exist inherently in some form or dimension, but in the same way your ego does, or psychological archetypes. They might not be "real" in the conventional sense of the word, but you could say the same thing about the entire psychedelic experience. I don't think that they could be considered any less real than your sense of self and identity--they are a product of your mind, and your experience of them was real. But regardless, even if they do just exist in your mind, they are an extension/manifestation of reality simply by that.
Just my take on things though. I wouldn't take anything I say
too
seriously
EDIT: I've also realized on a lot of my trips that technology is not separate from nature and not entirely 'our' doing. Technology is an extension of nature, and ultimately everything comes from the earth, comes from nature (which is universal in scale, not just limited to our planet). So I wonder what kind of questions could be asked from looking at evolution and life through technological innovations over history??
My take on it is that an inherent quality of life is evolution, and everything evolves. Virtually everything in existence has that life force within it that fuels change and adaptation. And really think about it, it's not just animals and plants that evolve. Technology evolves for sure, that's a given and you don't have to look very far back in history to see for yourself. Language evolves and adapts over time and location, philosophies evolve, governments evolve, even your own thoughts and sense of identity changes and adapts over time. It doesn't have to be physical or obvious, everything in every form and dimension goes through adaptation and change; the universe is in a constant state of flux. From this perspective, is it not safe to say that subjective experience changes over time? I'm sure we perceive the world much differently than our early hominid ancestors. With this line of thinking as my basis, I would think it's more than safe to say that the psychedelic experience may have been somewhat different (in this regard) thousands of years ago from what voyagers experience today.
"Consciousness grows in spirals." --George L. Jackson
If you can just get your mind together, then come across to me. We'll hold hands and then we'll watch the sunrise from the bottom of the sea...
But first, are you experienced?