I don’t think we know what original really is to make a meaningful distinction between derivative work.

With enough mixing and matching and a tiny bit of randomness, I bet a lot of original thoughts could be created.

These things are hard to quantify but ChatGPT writing does have a certain anodyne character, in my mind, when I read it. Then again, I can't quantify it, I could be biased by my foreknowledge of the writing's provenance, and even if I'm right, the world is full of situations where bland writing is suitable or even desired.

It absolutely does. It’s wishy-washy nature is harder to disagree with, sounds more credible, etc.