> Where does that come from?
It comes heavily from what you've been taught is important, which, funnily enough, is culture-dependent. A good many people would, for example, argue that a person has a right to shelter and sustenance, and to demand that from others when they can't access it - but other people will argue that people have a right to refuse to give resources to others, even up to the point of refusing taxation. One might argue that one has a right to work without discrimination or harassment - others might argue in favour of freedom of association and free speech, "if you don't like it you don't have to work for them".
To move even further away from currently implemented systems, one might argue that private property is not a right, which is actually entirely reasonable - property is solely a "right" to abridge others' rights, if we're going by the "what's a right is whatever you're allowed to do if nobody stopped you" definition. We could even argue that the ability to break a contract without retribution must be protected as a right, in some schools of thought. What rights "should" be protected - and in what circumstances - winds up being a matter of the opinion of the people who decide which rights to protect. There is no formal system of logic which starts off with no assumptions, and many of the ones which back politics start off with the goal - to protect people's rights, we must... protect people's rights.
Even the idea that a founding document should primarily enumerate rights is because of what you've been taught - why not enumerate duties as well, or instead? Why not write a manifesto with a general goal and proposed method of getting there and call that your founding document? What even is the goal of a founding document?
Why is abridging your ability to do whatever you want to any degree abhorrent - and why is abridging that ability in certain circumstances not so? Is it impossible to come up with a stable system which holds up a different ideal?
I don't really expect all these questions to be answered, as the exact answers are nearly entirely pointless - the point is that these questions can all be asked and different answers can be reached, many of which make sense.
For example, an argument that nobody has a duty to feed and shelter somebody on the edge of starvation, as that harms the person doing so, entirely ignores the harm that this protected right has on the person about to die of starvation - although of course to bring that up requires that the goal of your system of protected rights is to reduce harm, which may not be the case. However, the only way "we must protect all these listed rights at all costs, ignoring all other input" makes sense is if the goal of your system is solely to protect those rights. I don't personally feel that's a very useful thing to do, as it's tautological. A good many people will disagree.