> I have never met a human who has a good grasp of what they know and don't know

yep. There are 2 processes underlying our behaviors.

1) a meme-copier which takes in information from various sources and regurgitates it. A rote-memory machine of sorts. Here, memory is populated with info without deconstructing it into a theory. This has been termed "know-that". Here, explanations are shallow, and repeated questioning of why will fail with: I was told so.

2) a builder which attempts to construct a theory of something. Here, a mechanism is built and understood, and information is deconstructed in the context of the mechanism. This has been termed "know-how". Here, explanations are deeper, and repeated questioning of why will end up with: these are the "givens" in our theory.

Problem is that we operate in the "know-that" territory most of the time, and have not taken the effort to build theories for ourselves in the "know-how" territory.