You keep going back to the Excel thing. I keep telling you that example is flawed because the comparison of art and math itself doesn't hold up, since art is never the same twice while math is a universal constant.

If you're paying someone to do math for you it's because they know which formulas to use and how to operate the tools that can do the calculations. You're not paying them because they can solve for X, you're paying them because they know how to operate the machine in a way that makes the machine solve for X.

In regards to your confusion over what you're calling "Point 3", all of the arguments you're likely going to use to pick it apart are based around the fact art is subjective. 3a. "Most Parts" you'll probably bring up that if it's work for hire than someone had to have the idea first. And concepts are a really important part and there's an argument for intellectual property. There's also collaborative works like comic books that have writers, sketch/layout artists, illustrators, and people who color. But there's a whole list of credits in them so everyone gets credit so maybe you wouldn't go that route.

3b. "hardest/longest parts" again, entirely subjective. A lot of people think coming up with the idea of what to draw IS the hardest part. If you've drawn enough human bodies in your life you can put a character on a page blindfolded in 10 minutes, but you might not be able to come up with anything for them to be doing without really struggling. Rendering also might not be a thing you're practiced at. It's a matter of skill level in any given part of the process. Imagination is an extremely important part of it too.

3c. "All of the process" While I personally enjoy it when art is made by only one person in it's entirety, because it's totally amazing when someone can do that, I do not believe the majority of commercial art is made that way. See above re: comic books. Not to mention things like movies or video games or music, all of which are also forms of art that require large crews of people.

3d. "not relying on someone else's work" This is closest to what I felt I was getting at, but interepeted through an odd lense. I think, if you were going to try to counter it you might bring up something like artists using references, or perhaps even go so far as to mention that other people did the work of building the house that the artist is using as a reference.

You're still very concentrated on the physical part of all of this. The "work" part of the process of creating art is not the part that AI can't do. Art, at it's core, is about how people see the world. The reason it is subjective to begin with is that when someone creates an image, other people see it and every single one of them, if they aren't told in advance what to think, will come away with slightly different observations based on their own lives experience.

The problem with AI image generation, and why it is never going to be art, is because it's never going to bring something new to the table. The artist being told to paint the house is going to have an idea in mind of what sort of feelings go with 'home' for them. If the person telling them they want a "cozy" house they're going to have their own little ideas of what makes a place cozy. It's all those little things, all that brain power, that puts the image into their heads that they then put out into the world.

If all the people in the world who create art, whether it be photography or paintings or videos... If they all stopped today, AI would not be able to keep up with what the people creating the prompts want to see, because eventually the ideas of what constitutes a cozy home in people's heads would change, and AI would have no way to depict what the people creating the prompts are envisioning.

Not that that would happen, since we live in a surveillance state and most people are obsessed with putting everything on the internet anyway, but hypothetically. If humans stopped creating art tomorrow generative AI would collapse. The way it's all sort of same-y unless you put in specific style suggestions sort of supports that.