Have you ever actually bothered to look up at the sky? More than 50% of the time in any given location – some more than others – it is NOT blue! Even when it is partly/mostly blue there are generally other colours up there! And even when it IS entirely blue, on a perfectly cloudless, sunny day (and even disregarding the non-blue colour of the sun) – there are different SHADES of blue – some of which are closer to purple or other adjacent colours!
The sky can be made up of various parts blue, gray, brown, red, orange, black, purple, white, green, yellow, etc… It also contains literal rainbows sometimes!
“What colour is the sky in your world?”
What a stupid question. There is no single answer – it contains all the colours, and it always changes, and it is never 1 unified colour for the whole sky around the whole world!
What kind of moron would answer “Blue”?