Once again, being reductive about artists' work. Jackson Pollock's entire career was smashing colours on a canvas. If you want to argue that Pollock had to look at thousands of paintings before making his, I honestly can't take you seriously at that point.

A computer could easily generate such “work” as well with no training data at all.

Yes and in the eyes of its creators, that was deemed a failure which is why Midjourney and Dall-E are the way they are. These bots don't want to create art, they want to imitate it.

Children have barely any experiences and can still create something. You might not deem it worthy of calling it art but they created something despite their limited knowledge and life experience.

Of course, you'd need books to read and write. The words have to be written and you need to see the words in written form if you also want to write them. But one thing you don't take into account is handwriting. Another thing that is unique to every individual. Some have worse handwriting than others and with practice (like any muscle) it can be improved but you haven't had to have seen handwritten text before writing it yourself. You only need to be taught how to hold a pen and you can write.

Novels are complex structures of language just like poetry. In order to write novels, you have to consume novels because it's well understood that to find your own narrative voice you must see how others express theirs. Stories are told in unique ways and it's crucial as a writer to understand and break these concepts down. Intention and purpose form a core part of storytelling and an LLM cannot and will not be able to express those things.

They're written in certain ways because the author intended them to be that way, such as Cormac McCarthy deciding to be very minimalist with his punctuation.
I would love to see you make a point that an LLM without being specifically prompted to do so would make that stylistic decision. An LLM can't make that decision because unless you specify a style it is aware of, it won't organically do it.

I am also a writer. I've written a short story. One of my stylistic choices is that I don't use dialogue tags like "said". An LLM won't make that choice because it isn't designed to do so, it won't decide to minimise its use of dialogue tags to improve the flow of the narrative unless you told it to.

It’s also completely ignoring the fact that you had to previously learn the spoken language as well (which is a vast quantity of information that takes a human decades to acquire proficiency in even with daily practice).

Yes, in order to learn a spoken language you have to have heard it. However, languages evolve over time. You develop regional accents and dialects. All of the UK speaks English but no two towns speak the same way.