What Are the Blind Spots of Humanity?

What makes mathematics valid? That's a much deeper question than most people give it credit for. What are the limits of rationality? Or is rational a feature of the human mind, and maybe it's a projection upon reality? What is more reliable? The senses? Are five senses, rationality or intuition? Which one of those three should we use to develop our knowledge? Also, what are the biases and blind spots of humanity as a whole? This question i love because it's rarely considered.