I suspect that what you have written is largely on the right track. Extended human perception and quantum effects (clairvoyance, remote viewing, telekinesis, etc.) were common to humans back when the food and water supply was clean.
I haven't seen anything to suggest that racial intermarriage decreases these abilities (in some cases it may make them stronger though). However, there do seem to have been several extraterrestrial interventions on the planet over the past 300,000 years which involved tinkering with human DNA. Some of those tinkerings do appear to have had the goal of limiting human 'psychic' ability, for lack of a better term.
The philosophical movement deviously called the 'Enlightenment' (Lucifer's light, I guess) also helped limit plebs' use of their higher abilities because it deceived and ridiculed so many into believing they don't or can't have them (or that they are 'demonic').
Looking at world literature from the 17th century, it's clear that in every corner of the globe, people were regularly using their higher mental abilities to interact with the non-physical world. As socialist/illuminist education, along with the mind-killing vaccine additives and crop contaminants, has spread to nearly every nation, the situation is very different today.