Let's take one style of painting, say Jackson Pollack. You wave your brush around over the canvas. It's copywritable.
Now you create a frame that holds the brush that randomly shakes it using a shop motor over the canvas. Still copywritable.
Next, you plug it into a computer and have the computer use a RNG to determine how to shake it. Still copywritable.
Lastly, you have an LLM generate a sequence of angles and velocities with which to shake the brush. No longer copywritable? Why?