You can see blue, because you have a word for it

[tw]

Mankind changed significantly when his diet improved. For example, by eating meat and cooking food, then the humanoid brain increased significantly. Retinoid is another dietary contributor to vision. As retinoid increased in diets, then cones shifted from detecting mostly red (low frequency light) to also detecting higher frequencies (blues).

Retinal is also more commonly made available as Vitamin A. That theory is more based in science and not in vague speculations.