Freedom of Speech: Is This "Right" Just a Social Construct?

Article 19 of the the 1948 United Nations Universal Declaration on Human Rights states: ""Everyone has the right to freedom of opinion and expression; this right includes freedom to hold opinions without interference and to seek, receive and impart information and ideas through any media and regardless of frontiers." Of course, this is not absolute. We are aware that freedom of speech may be restricted; for instance, free speech doesn't include incitement to imminent lawless action; genuine verbal threats of violence; defamation by slander (speech) and libel (writing), obscenity; child sexual abuse material, fraud and perjury; special contexts (e.g., school or workplace speech limits); undermining national security interests and wartime activity; neutral government restrictions (e.g., quiet zones, noise ordinances, etc.).
Given these matters, why is freedom of speech so critical? We could also speak about other freedoms--of conscience, of assembly, and so on. But what is a right and why is it important? We assume rights as part of our Western vocabulary, but some will claim that rights are a Western invention--a mere construct.
What do we mean by a "right" of free speech? Is this just something a government bestows? Is it a "social construct"? Or is it something non-negotiable, which no government can either bestow or take away? And where do rights--free speech or otherwise--come from?
Someone from our group suggested that we discuss rights--like the freedom of speech. So we'll look at the important of free speech and also discuss the nature of rights themselves.
Come join us. We are meeting on a Sunday rather than a Saturday--and a bit later in the afternoon. I'm looking forward to a good discussion with you all!