True we are learning at the pace we are capable of but if you look at it in a different perspective, we human are able to absorb large amount of knowledge and information accumulated or passed on from generations to generations.

The struggle I believe is to explore new knowledge.

Like an infant, first it would appear difficult to grasp the most simplest idea but once we master it we are open to a whole level of knowledge and understanding.

As times goes on mankind will struggle with more complex ideas than the previous generation.

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So to answer your question, how do we learn.

I would say we learn by interpreting and making sense of the things around us with the knowledge we have.