? On install I always set my own wallpaper, in this case my wife on vacation in a swimsuit on a beach in Sydney Harbor.
Only use I have for the as installed wallpaper is that I can read the text. Some wallpapers are hard to read.
Some Ubuntu's require a number of mouse/keystrokes to set the wallpaper, example Lubuntu.
Ubuntu pretty easy, copy your desired jpg into Pictures and select with Appearance.