It's not just training data going into the result, the user is responsible for prompting and picking correct formulations, or fixing or discarding. So it's still semi-manual work. It's just Copilot, not yet full Pilot. The copyright should belong to the human assuming they could have written the same code if they had access to search the internet for help. So it works like a search engine when it's replicating verbatim. Should be considered similar to coding with access to internet for answers.