Re: ....unless they can prove its not copyrighted
"On the one hand I agree with you, on the other.... well, if I create something completely new and own the ip for it, why should you be entitled to presume it belongs equally to you and to my decendants?"
Let me be less facetious with an answer. There is a different between property and IP, which is why it has the I at the front. IP is not property. IP is non-enviable, which means that if I 'steal' your IP, you still have it. So since IP cannot be stolen (without some form of memory-wiping drugs), it isn't property. This is why we distinguish between the painting itself (which can be stolen) and the idea of the painting (which cannot).
It is ludicrous to suggest that IP should be owned in perpetuity. For example, you like chairs? How about paying the descendants of the first chair maker to sit down? Every product has an inventor, who in the world of perpetual IP would rake in fees. Each person that contributed to the development of the computer, the motor car, the aeroplane, etc., would be due a royalty every time one was made, maybe even used? And each could presumably say no, we won't license the IP for rubber to be used any more, find a new compound. You could make something like rubber 'essential', so set FRAND-like terms for it, but as time goes on more and more cash would have to be set aside to pay all previous inventors.
You might wish now to distinguish between different types of IP, between 'useful' stuff, which is owned by everyone and inventors cannot perpetually assert their rights, and 'useless' stuff, which can be owned in perpetuity by its creator. But this demonstrates precisely why it makes no sense: the act of creativity is the same, so why should one be denied what the other enjoys? It sounds like nothing more than special pleading on behalf of those who make 'useless' stuff.