WHY BLUE IS INTERESTING: The myth that BLUE was unseeable until modern times.
THE SCIENCE BEHIND SEEING COLOR:
Vision among vertebrates is a result of having specialized light receptor structures known as rods and cones at the back of the eye in the retina. Rods are extremely sensitive to even dim light but provide relatively coarse, colorless images. Cones provide the sharpest images and are responsible for the ability to see color, but they only function effectively when the light is bright. Consequently, all vertebrates are more or less blind to color in the dark at night. Different types of cones are "tuned" to different portions of the narrow visible spectrum of electromagnetic radiation.Near the surface of the cones are light sensitive protein pigments called opsins. The opsins in different cones are sensitive to different wavelengths of light. Colors are identified by the brain based on responses from the different opsins. The key to color vision is the ability to differentiate between different wavelengths. Humans are trichromatic (literally "three colors"). They have three different kinds of opsins on their cones which allows them to discriminate between blues, greens, and reds. Some scholars suggest that being able to choose ripe fruit and edible berries may have influenced the selection of colour-categorising vertebrates.
THE NEUROSCIENCE BEHIND SEEING COLORS
Light itself has no color. The color of a specific wavelength can change according to context. Color is used to allow us to interact with our environment. Neurobiologically, we all see the colors, but we see them as another hue of a color we have defined. The brain will increase the difference in these hues as we define them making them easier to identify. Although the visual system is the most scientifically studied system of the brain, it is still unclear where our ability to see colors comes from, and the processes involved in the conscious perception of color
The Business Insider Article: No one could see the colour blue until modern times
HISTORY OF BLUE
https://www.sciencealert.com/humans-couldn-t-even-see-the-colour-blue-until-modern-times-research-suggests (Business Insider article summarized)