iPhone OS 1.0-3.0
The original iPhone
Plain black. Apple didn?t like wallpapers that time.
iOS 4, iOS 5
iOS 4 introduced multitasking and the ability to set the wallpaper. This one was the first which was promoted on marketing screenshots.
iOS 6 had a stylish, blue ripple as the default wallpaper.
iOS 7 changed everything, including the wallpaper. Even if the OS supported dynamic wallpapers now, Apple used this image as the default.
Light beams under water
iOS 8 sticked at the blueish colors.
iOS 9 beta
iOS 9?s public beta version introduced a very attractive wallpaper.
I really don?t know what this is
iOS 9 had a new resolution for the default wallpapers (on iPad): 3208×3208. The image above is rescaled, because the original file is 26 MB, and Medium allows images up to 25 MB only?
Another wave, this time recognizable
Elegant new wallpaper.
Ocean coast with waves
Calm blue and sand colored image.
?An explosion of crimson rips asunder blue-green fractal generatives masquerading as paint striations.?
Vibrant red and blue colors.
The light version of the dark/light default pair.
iOS 13 introduced Dark Mode, and comes with a set of wallpapers which have a dark and a light variant to match the currently selected theme.