Thanks for this perspective @rok-sivante it resonates with me and correlates with what I have been pursuing myself recently. I believe that the reason for the deficiency in energy as you have described is due to us being in this three-dimensional form and forgetting how to breath Prana and how to consume light. The reasons behind us forgetting these concepts that are necessary in order for us to maximize the strength of our physical body - light body connection and thus access to our full potential is up for discussion, but the heart of the issue is that the energy source that fuels our conscious evolution and allows us to gain access to extrasensory perceptions beyond the basic 5 physical senses is not food, water or air.
The energy source has been known for all of human history and called by different names such as Prana or Chi, or more recently Energy, Bio-Energy, Vital Energy, or whatever you want to call it. This energy exists and is real regardless of one's ability to perceive it with their 5 senses, much like gravity. This source is the only power great enough to replete the body, brain and consciousness with the energy you perfectly described we are deficient in.
I have been putting conscious effort and focus into remembering how to breath Prana, and the more I practice it, the more awareness and comprehension I gain of senses and perceptions beyond the 5 physical. As you explained, the reason everyone doesn't have access to perceptions beyond the physical is not because they don't exist or that they aren't capable, it's simply that they don't have sufficient energy to supply the faculties.
In addition to breathing the breath of Prana, I find the concept of consuming light as nourishment very fascinating. Specifically, the work of Fritz Albert Popp and his research on Biophoton emission. It is my belief that we do not consume food at all, as in physical nutrients. What we actually consume and use as energy are the Biophotons that are emitted from the food that we consume.
Your analysis here is the why behind it that ties it all together. Looking forward to going deeper.
Breath is one part of the puzzle, indeed, and can be used as a training protocol for the brain to increase its memory processing capacity. T'is all a bit of a complex system, though you definitely are thinking in the right direction to start...