> should never be possible for someone to sign away their rights. If you can sign them away, you can be swindled of them.
So, if I sell you my house or car I can't sign away my rights on it? - Sure, there is a difference between material and intellectual property ...
Against swindling there needs to be protection from fraud, but that exists in most legislative systems.
You can't sign away your copyright in germany, you can only hand over the rights of distribution of your work.
Tangent to your point, the Bible requires that home ownership work exactly like this. You can sell your family's home and lands, but every 50th year, the Jubilee year, the lands must be returned to your family.
The intent was to prevent permanent poverty (poverty = not owning land), and any slaves are also freed on the Jubilee (because slavery was also a poverty thing then). Today, though, it'd probably be more of a tool of a permanent ruling class, so it's probably a good thing that Jews and Christians mostly ignore that section.
"you wouldn't steal a car" again?
You answer your own question.
Yes, intellectual property rights should be different than physical property rights.