Isn't most creative work synthesis rather than unique whole-cloth creation? Look at what happens with software when it is open sourced and allowed to be remixed freely. Are we better or worse off because of it?
There's nothing that prevents people from remixing things that are not copyrighted and create something amazing that others are interested in or of cultural value.
With open source, I should note, its remixing is in fact governed by copyright.
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.
With open source, I should note, its remixing is in fact governed by copyright.