Which is to say they didn't have much of an idea at all, because it really didn't exist in much the same way. In fact, this is still a inaccurate characterization for exactly that reason. On the basis of copyright, take for instance the idea of exclusive rights to print a work. This actually wasn't implemented as a method of protection for the author, but a political reaction to the printing press being "misused" in the eyes of the anglo-colonialist entity controlling the British isles, and so was a means of preventing the mass creation of undesirable literature.
On the basis of patents, it didn't quite have nearly as much of a history of mutation culturally, but did experience massive whiplash in purpose and application following the implementation of globalism. What was once a system to protect technical innovation on an individual level, would find new purpose as a means to provide structure to an increasingly complicated and internationalized dynamic market. Another means of bureaucratic organization. Then, once again, the context and purpose would change when the world developed digital globalism. The entire engine of IP as a legal fiction became a significant geopolitical tool in an increasingly cramped and fragile world, a necessary gimmick holding up the sky.
Unfortunately, not much to do at this point. It'll likely only become even more nonsensically important as time wears on, until the globalist system collapses. It's certainly possible it'll even be the confounding factor that causes the great unraveling, though the problems hardly begin and end with IP. It was just a useful legal fiction in the wrong place at the wrong time.