If an artist trains an image generation AI on their own digital art catalog, should they be able to get a copyright on what it produces? When does a tool change from a tool to a non-human creator?

Under US copyright law, only works created by humans can be copyrighted. Courts have (imho rightly) denied copyrights to AI-generated images.

My question is when do you think AI image tools cross from the realm of a “tool” (that, for example generates and fills in a background so an item can be removed from a photo) into the realm of “a human didn’t make this”?

What if an artist trains an AI so specialized it only makes their style of art? At what point do you think the images they create with it begin to count as their “work product”?