than most of our brains represent, perhaps ... but clearly there are people who see things others don't ... give them the ability to see at these scales, and enough explanatory skills, and perhaps it will become something even a child can understand.

A dog is never going to understand Fourier Transforms. I expect there are concepts that our brains will never understand as well.

Indeed, it’s an uncomfortable idea but maybe someday we’ll have to accept it. That we don’t know, we’ll never know, we can’t know. I wonder if we’ll be able to prove that we can’t know something. Or prove that we can’t prove it.

Or, alternatively, the human brain, unlike dog’s, has the capability to learn (and eventually understand) that may already exceed what is needed to understand all there is to understand.

Brains. One person may not be able to understand it might take teams.

Personally I think it's because we're "looking" at it from the wrong angle. A bit like in programming when you're stuck and you need to take a step back and approach the problem differently. IMHO the fundamental construct is probably something way more abstract, i.e. "information", with some laws that we aren't even aware of yet that will probably challenge the principle of locality.

This. It’s bad philosophy. Non local, non physical, these are the concepts to get comfortable with before attempting to understand the quantum in a coherent way, unless understanding the nature of physicality and locality isn’t your goal. Looking at the quantum world as a bunch of tiny objects will only lead to an infinite regression, where new even smaller objects are continuously discovered.

I think we are still in the "universe orbits the Earth" stage of quantum physics.