if you presented both the generated image and the "original" to a jury of peers (or even a panel of experts in the field), they would be able to make a determination as to whether the generated image violated the copyright of the presented "original".
Humans tweaking the image is immaterial to this determination - if the human tweaked it so that it no longer seem to violate copyright, then that said panel would also make the same determination.
You are arguing that AI generated means no copyright protection. So you can't tweak it to "not violate copyright" because their literally isn't any.
Of course you have no way to prove whether any image was or was not generated by AI so welcome to a new scam for law firms to aggressively sue artists claiming they suspect AI was used in their works.
Humans tweaking the image is immaterial to this determination - if the human tweaked it so that it no longer seem to violate copyright, then that said panel would also make the same determination.