>> A computer absolutely can not create original work.

> Why not?

> Or rather, if a computer can't, what is the reason that a human could instead?

It's a question of the word "original". Water makes beautiful patterns in the sand below it, wind creates intricate patterns on the water. But we don't usually use the phrase "original work" to talk about things like that. Its meaning is related to the concept of invention, something that takes a will, a desire, imagination, intentional work, skill, and a process that involves being conscious of the aesthetics of what's being produced. I think that some animals are capable of it too, to some extent. But things produced by inanimate forces just don't fit into the category by that name. It doesn't mean they're not beautiful, and they have been the inspiration for countless artworks. But they're not called original artworks in themselves. There are different words for that.

On the other hand, people use tools and media to make art, and an artist using a computer can certainly create original work, if it involves the elements mentioned above. Also, processes of chance have been extremely important in the art of the past century. Much of the "output" of John Cage's work for example, is based on randomness. And I don't think the US Copyright Office is a particularly good judge of that. They might refuse to register a copyright on the music created, when musicians played notes that were produced by fish in a tank with a musical staff painted on it. Nevertheless, that piece is considered a very important and original work in the history of avant-garde art and music.

One of the best examples is artist Harold Cohen's AARON, a software project started in 1972, that produces physical paintings, spanning over four decades. The artist himself doesn't claim that the sofware is "creative", though the paintings have been displayed in many important galleries, and the overall work is considered very significant and influential in the history of art and AI. In 1994, Cohen asked: "If what AARON is making is not art, what is it exactly, and in what ways, other than its origin, does it differ from the 'real thing?' If it is not thinking, what exactly is it doing?"[1]

It comes down to the nature of the work. Someone who writes "an astronaut riding a horse"... it's so low-effort that it's difficult to call it original art, even though it's become somewhat iconic. But I don't think at all that its impossible to use AI image generators in a process that does produce original, creative art works, or at least, in a way that the deep and thoughtful investigation of the questions, as in Cohen's work, is clearly the original work of an artist.