However, the brain is a remarkable thing, but it is certainly not infallible. There are many, many ways in which our ability to understand some things is limited. What we see may not be there, what we remember may not have happened. We can be very wrong about things we think we understand (the Monty Hall problem is a good example of this – the page displays weirdly in my browser, so scroll down). If you study Psychology at Uni you will find out a lot more about the limits of human understanding.
Scientists in general recognize this fallibility which is why we’re always keen to test what we think we know with experiments.
The brain is a truly astonishing organ – often said to be the most complex thing that we know of in the whole universe.
To develop your capacity for understanding it is important to train your brain – to fill it with information but also to learn how to think about connections between facts. The more time you spend on that, the more you will understand about the world.
But, as you ask, are there some things that are just too complicated to understand? That is true of me – there are aspects of physics (e.g. Einstein’s general relativity) that I do not have a firm grasp of at all. I think I might be able to understand if I worked really hard at it. But my problem is that I don’t have the time any more.
Then there are big questions that just boggle my mind and I can’t even begin to think of an answer. For example ‘Where did the universe come from?’. That’s a huge question that seems to be beyond anyone’s understanding.
Maybe you will be the one to crack it? If you want to have a go, good luck!