ST7735 display and picture and pictures

Maybe you could try just setting up the display without images and trying out some colours to make sure it's working right. Looking at what you said above:

0000FF = yellow
00ff00 = blue
ff0000 = black (no color)
ffffff = white

My guess is the screen's colour format is 16 bit BGR565 (BBBBBGGGGGGRRRRR). However it could be that the byte order is wrong, which would explain a lot. In that case it'd be something like GGGBBBBBRRRRRGGG which would be super confusing.