Sure. But in addition to copyright you might add the concept of money, or the concept of any property rights and ownership of physical things, and...

Calling such things "shared delusions" is missing the point...it's not that it's wrong, but it is not a very useful way to look at it.

There is such a thing as intersubjective (as opposed to objective) reality. Physically it exists as a shared pattern in the brains of humans, but that is seldom useful to reflect on. Language wise much more convenient and useful to talk about copyright as something, you know, existing.

Everyone knows these are just human agreements... it is not exactly deep thinking to point it out.

You may not agree to some laws. You can then seek to have the laws overturned (I agree patents and copyright are... counterproductive, at this point). Luckily many parts of the world have democracy to decide what laws to force on people, as opposed to a dictator.