After searching for the 1.14 textures ported to 1.8.9, I discovered that many of them are not complete or changed other things besides just the textures. So, I spent a day porting the textures from 1.15 to 1.8.9 without adding anything extra. The block textures, items textures, and texts were ported. Note that some entities such as the donkey have different shapes in 1.8.9 and prior, so I was unable to port the texture.
Download latest version here: