What things are not copyrighted? Anything someone makes is immediately copyrighted. If you mean take a couple hundred years old content to remix, well, I don't find that very useful and certainly not how human history has worked all this time.
You are right that in most countries (including the US) copyright protects a work automatically the moment it’s fixed in a tangible form.
I think we’ve veered a little off the original thesis where we started which is an argument that copyright is limiting the rate or breadth or level of cultural artifacts. I have to say that I find it hard to imagine a meaningfully higher volume or level than we already see today. I mean are you worried that we’re stifling creativity? I think it is abundant and the evidence is all around us.
