No such assumption is made in the article.

Nor does it give a single answer.

Mere prompting is still not enough for copyright, and the problem is unsolved on how much contribution a human needs to make to the generated code.

In the case for generated images copyright has been assigned only to the human-modified parts.

Even worse, it will be slightly different in other nations.

The only one that accepts copyright for the unchanged output of a prompt is China.

Here's a question I have: if the AI generated image is of a character of which you own the IP, don't you have protections based on the character regardless of who gets copyright protections from authorship of the image?