What's the simplest thing humans are too dumb to grasp?
You ever see a dog that's got its leash tangled the long way round a table leg, and it just cannot grasp what the problem is or how to fix it? It can see all the components laid out in front of it, but it's never going to make the connection.
Obviously some dog breeds are smarter than others, ditto individual dogs - but you get the concept.
Is there an equivalent for humans? What ridiculously simple concept would have aliens facetentacling as they see us stumble around and utterly fail to reason about it?
Reality is equal part abstraction and physicality, energy and information are two sides to a coin we are currently unable to percieve in full. Also, there are some aspects to reality that will never be able to be understood through the lens of science or math, due to their need for falsifyable truths within a working model. Some truths cannot be proven, and some non-physical aspects of reality cannot be directly observed through lenses or interacted with sensors or broken down into particles. The moment we start examining conciousness and psychadelics seriously as a new avenue of understanding reality our collective understanding of the universe in its totality will skyrocket.