Copyright is automatic at the time of creation. You just need to be able to prove you made the first copy. That's how it works in creative works.
Timestamping will solve this. We could even put up a bounty for novel ways of doing this if there's a need.
In poor artist land we would just snailmail manuscripts to ourselves.
Easiest way to do it years back.
Or we would go to the tax office to get an official stamp from them with a date on it.
Ah, the days of yesterday... *cue melancholic music*