Do they seriously expect us to make art like the one in the game page? Or was that supposed to be ironic?

It is to draw inspiration for a theme and setting in your game, if they expected that it wouldn't be 2 days with ms paint.

The goal of the theme was to simply draw inspiration. My idea originally with the painting themes was to just play on the fact that this is a "paint" jam. Feel free to take the theme in anyway you want, or not use it at all. Trust me when I say this, I'm running paint jam mainly as a way to show that games can be fun even without insane next-gen graphics.