Because science was not advanced enough to detect and measure 6th and 7th sense energy fields, such phenomena was illegitimized as paranormal, and even ridiculed.
Sixth sense experiences range from intuition, déjà vu, prescience, to past life parallels. As our conscious mind is always trying to create a linear story out of our experiences, we tend to look for cause and effect to explain a multi-dimensional event. When our mind can’t make two and two equal four, we call it a coincidence.
Some “sense” can be made of all this when you understand that your primary senses are inseparable from your chakra system. Chakras are multi-dimensional vortices of energy, as levels of consciousness, resonating at specific frequencies that also line up with the notes on a musical scale. Chakras act as an interface between the dense physical world and the non-physical world of pure consciousness. There are seven notes in a musical scale, seven chakras, and you have seven senses.