1. Because it’s not human. We distinguish ourselves in everything, that’s why we think we’re special. The same applies to inventions, e.g. why monkeys can’t have a patent.
2. Time. New “products” whether that be art, engineering, science, all take time for humans. So value is created with time, because it creates scarcity and demand.
3. Talent. Due to the time factor, talent and practice are desired traits of a human. You mention that a talented human can do something in just a few days that might take someone else years, but it might only take them a few days because they spent years learning.
4. Perfection. Striving for perfection is a human experience. A robot doing something perfect isn’t impressive, a human doing something perfect is amazing. Even the most amateur creator can strive for perfection.

Think about paintings vs prints. Paintings are much more valuable because they aren’t created as quickly as the prints are. Even the most amateur artwork is more valuable as a physical creation rather than a copy, like a child’s crayon drawing.

This even applies to digital art because the first instance of something is the most difficult thing to create, everything after that is then just a copy, and yes this does apply to some current Gen AI tech, but very soon that will no longer be the case.

This change from humans asking for something and having other humans create it to humans asking for something and having computers create it is a loss of our humanity, what makes us human.