If you want to argue against AI you should use better arguments.
It starts by not applying the word stealing wrong. If I steal from you, you no longer have the thing I stole. What you really mean is, used without consent.
And it is debateable, if consent is necessary in all cases. Furthermore, as soon as you have an AI that does not retain the stuff in its database, your argument is invalid.
This is because putting your stuff out there will "train" humans as well. They could imitate your style and the determination if they "stole" your work, is not by method but by result. And this is currently true for AI generated work as well. I can not use AI to plagiarize your work and get away with it, just because I used AI.
But I can very well use a human trained or programmed machine that will replace your job in about any other context and no one bats an eye. (Ok, they would, but not about the method, only about the result.)
My point is, if you fixate on such details about AI, your arguments will not hold true for more advanced AI. So better start now with having future proof arguments.
Oh, and it is creative work. Do not underestimate the work needed, to create good looking AI art. It is lots faster and needs different skills to make it, but it is still a human doing that work. Just like you still have a human operating those factory robots.
That thing with the derivative work, where is the line? There obviously has to be one, since there is a smallest unit, like a pixel and even with concepts, like mysterious smiling woman with crossed hands. If I rearrange parts of an orginal work to create a new work, when does it stop to be derivative? When is it considred a new work? Especially if I use more than one original works and blend them as inspiration for my new work. If a human could do it legally , forbidding the use of machines to do it, is very hard. And you could even start from scratch, because this type of visual art tries to imitate nature. Like painting a portrait or a landscape. So is art actually derivative of nature? Where is the original originality? Is it turtles all the way down? One artist copying from others till you get to nature?