How will copyright not help here? You don't have to use the same code or assets for something to be copyright infringement. It's one thing if you personally don't believe in copyright, but just claiming that it has nothing to do with copyright because it's not a 1:1 copy is just not true.

If you made something that "just happens to look like that other thing", you'll have a hard time defending that in court (especially if you extort them beforehand). Heck, there have been copyright lawsuits over musicians using similar lyrics or melodies since forever.

Training data is based on copyrighted material that is stolen. Someone should be made to pay somewhere. The theft of human thought cannot be allowed to be exploited.