Copyright is good and should be enforced. I say this as a person who doesn't hold any copyrighted materials. Anyone pro abolishing it is deluded by the "free market" myth, which is not possible in any form.
All owned by you and copyrighted by you, sublicensed to Y Combinator.
Your employer may have agreements in place where you assign copyright to them for any notes or code or other works you produce while at work. But if you draw a stick-figure picture in a notebook, that's your copyright.
You actually do hold copyright on everything you've written. For example, your comments here on HN: https://news.ycombinator.com/threads?id=Yizahi
All owned by you and copyrighted by you, sublicensed to Y Combinator.
Your employer may have agreements in place where you assign copyright to them for any notes or code or other works you produce while at work. But if you draw a stick-figure picture in a notebook, that's your copyright.