How can I learn who created a jpg?

You could check in photoshop for such data, but I think that that is mainly for GIFs that you can encode your name and such with it. Chances are the person didn’t bother doing this anyways.

You can try GOogle image search and search for a set of keywords that describes the image.

Exif data may not be recorded if your image is a copy. Try Tin-Eye. It can find other occurrences of your picture on the internet. It might help you, for instance if you find the photographer’s home page.

@downtide I always hoped there was something like that.