Amazingly, when languages evolve, they almost always create words/ name colors in the same order (called the hierarchy of color);  Black, White, Red, Green, Yellow and then Blue (followed later by combinations and variations like brown - derived from bronze, purple - of latin origin meaning both shellfish and splendidly attired, orange - actually named after the fruit, pink - one of the latest basic colors to get a name, etc.)

​

   Since it is the color we associate with both sky & the ocean, the most prevalent things on earth, one would think it would be named earlier, and yet the first colors named (after delineating 'dark'/ 'burn' & 'bright' with the words for Black & White) are the colors of blood, vegetation/ growth, and the sun.  Sky & Ocean were more prevalent, but they required less human attention for survival than warfare/blood and growth of edible foods, so Blue was overlooked for awhile. (Drinkable portions of water remember, while vital, are not very Blue, they would be closer to clear or murky tan depending on the source)

​

   Yellow was once a variation of the early word for Green (which, in addition to the color meant young/ immature, like the yellow-green color of new growth - and we still call an immature person 'green' today) But 'Yellow' eventually took on a sense of brightness related to sunlight and became it's own color. As such the early word for Blue was often interchangeable and confused with the early word for Yellow as both derived from the root word for 'shine' and described the general brightness of the sky (as opposed to the color of it.) But over time the two names evolved to describe different color aspects of that brightness and become the names for wholly separate colors.