It's actually the opposite of what you're saying. I can 100% legally do all the things that they're suing OpenAI for. Their whole argument is that the rules should be different when a machine does it than a human.

Only because it would be unconscionable to apply copyright to actual human brains, so we don't. But, for instance, you absolutely can commit copyright violation by reading something and then writing something very similar, which is one reason why reverse engineering commonly uses clean-room techniques. AI training is in no way a clean room.