SCOTUS hasn't ruled on any AI copyright cases yet. But they've said in Feist v Rural (1991) that copyright requires a minimum creative spark. The US Copyright Office maintains that human authorship is required for copyright, and the 9th Circuit in 2019 explicitly agreed with the law that a non-human animal cannot hold any copyright.

Functionally speaking, AI is viewed as any machine tool. Using, say, Photoshop to draw an image doesn't make that image lose copyright, but nor does it imbue the resulting image with copyright. It's the creativity of the human use of the tool (or lack thereof) that creates copyright.

Whether or not AI-generated output a) infringes the copyright of its training data and b) if so, if it is fair use is not yet settled. There are several pending cases asking this question, and I don't think any of them have reached the appeals court stage yet, much less SCOTUS. But to be honest, there's a lot of evidence of LLMs being able to regurgitate training inputs verbatim that they're capable of infringing copyright (and a few cases have already found infringement in such scenarios), and given the 2023 Warhol decision, arguing that they're fair use is a very steep claim indeed.

The Supreme Court has not ruled on this issue. An appeal of a lower court's ruling on this issue was appealed to the Supreme Court but the Supreme Court declined to accept the case.

The Supreme Court has "original jurisdiction" over some types of cases, which means if someone brings such a case to them they have to accept it and rule on it, and they have "discretionary jurisdiction" over many more types of cases, which means if someone brings one of those they can choose whether or not they have to accept it. AI copyright cases are discretionary jurisdiction cases.

You generally cannot reliable infer what the Supreme Court thinks of the merits of the case when they decline to accept it, because they are often thinking big picture and longer term.

They might think a particular ruling is needed, but the particular case being appealed is not a good case to make that ruling on. They tend to want cases where the important issue is not tangled up in many other things, and where multiple lower appeals courts have hashed out the arguments pro and con.

When the Supreme Court declines the result is that the law in each part of the country where an appeals court has ruled on the issue is whatever that appeals court ruled. In parts of the country where no appeals court has ruled, it will be decided when an appeal reaches their appeals courts.

If appeals courts in different areas go in different directions, the Supreme Court will then be much more likely to accept an appeal from one of those in order to make the law uniform.

IANAL but I was under the impression that Supreme Court ruling was very specific to the AI itself copyrighting its own produced code. Once a human is involved, it gets a lot more complicated and rests on whether the human's contribution was substantial enough to make it copyrightable under their person.