Currently several lawsuits are in the courts regarding copyright and AI. While these court cases are still in progress there is no definitive answer on whether the use of copyright works in AI training data is legal. The U.S. Copyright Office and courts have stated that human authorship is required for copyright protection. There is also the possibility of copyright infringement when using outputs created by generative AI.
Zarya of the Dawn
While a decision regarding the copyright of complete works produced by AI hasn't been rendered, there has been a ruling by the U.S. Copyright Office of partial copyright when creating a work using generative AI. Zarya of the Dawn is a graphic novel that was created using the AI tool Midjourney. The images which were created from prompts by the author were denied copyright. The text, which was created by a human author, was granted copyright protection. The work as a whole is protected but since the images were created with AI, they aren't protected from someone else using them in their work. The arrangement of the images was creative and viewed as "expression" therefore covered by copyright.
Copyright and Artificial Intelligence
The link above directs you to the U.S. Copyright Office website where you can find the current copyright policy for works with AI elements.
Open AI stance on ownership of work created with AI tools is as follows: "Subject to the Content Policy and Terms, you own the output you create with ChatGPT, including the right to reprint, sell, and merchandise – regardless of whether output was generated through a free or paid plan."