Here's something to think about that might blow your mind. There's a very simple but almost universally overlooked point about the erroneous assumption that "it's all IN your head."
Let's look at it experientially:
1. you're looking at a screen. neuroscience tells us the light waves come into your eyes, get transduced through a complex process - mysteriously - into visual experence.
2. The same is true of tactile sensations, sounds etc.
Now let's look at this thing we call the "brain." If you stick with this analysis, how do we actually know about the brain? Doesn't it require the same analysis?
Have you been in a neuropsychology lab? You see the 3 lb brain sitting on the lab table, and go through the same analysis - light rays bounce off it, go to your eyes, to parts of your brain.....
But wait a minute - isn't this a perfect example of circular reasoning?
Let's go back to experience and see if there may not actually be an incredibly simple answer - and interestingly, given all you've written on the limits of rationality, you may have fallen prey to some abstract concepts that leave us unable to see the obvious.
What is the single irrefutable fact of your experience?
Are you aware? Not attending, not aware OF, simply aware? Are you aware of existence, of being?
Even if you don't attempt to answer, if you understand the words, the only possible answer is yes. Let's use the word "conscious" instead (it has all kinds of conflicting meanings, but keep it simple - basic awareness of existence).
Take any scientific experiment ever done, how do we know anything about it?
Through sensory, emotional, and cognitive constructions TAKING PLACE IN CONSCIOUSNESS.
How do we know about the brain?
Through sensory, emotional, and cognitive constructions TAKING PLACE IN CONSCIOUSNESS.
There's not enough room to fill this in, but if you look at Bernardo Kastrup's 2 introductory YouTube videos to his analytic idealism, you'll see he's made a case which philosophers have been making for thousands of years, even back before plato's cave, and much better than The Matrix, but rarely has it been so beautifully and elegantly interwoven with scientific findings.