only in the past few hundred years has Humanity Evolved into the point of seeing Blue
The Egyptians had a word for blue thousands of years ago. Ancient humans (within historical times) were biologically the same as us, and were capable of detecting the same light as us. The "people couldn't see blue in the olden days" thing is just that most other cultures didn't have standard words for it, as far as we know, and the lack of a fixed word seemed to shape how it was described and conceptualised (usually by comparison to other blue things, or by description of the objects' other characteristics). The names we give to sections of the visible light spectrum are learned and arbitrary, same with where we place boundaries between the named sections. There are tribes in Africa who break green into several colours within their language, for example. We don't have a word for those colours, because they're all named as shades of one colour in our language. We might struggle to differentiate them because we're not practised in naming and categorising them, but we have the same rods and cones as they do.
I'm colour blind, so I know where you're coming from, but humans have almost certainly not biologically "evolved" to see new colours within historical times (super-seers aside, and they've probably been with us for all that time too). It's a language and cultural shift. We developed more systematic language for describing colour, probably as knowledge of dyes and inks improved, and this gave us better specificity and helped fill out gaps in terminology and conceptualising colours. Egyptians had a rare, expensive and prestigious blue dye in lapus lazuli, so they had an incentive to have a colour concept of "blue", whereas other cultures didn't.
(can't say I've ever had problems with UI elements in Elite, but I know colour deficits vary, would wholeheartedly support them adding a variety of different colourblind modes)