> not all such limitations are just
This might be the heart of your confusion. I’m not arguing about what’s just or right at all. I’m talking about what freedom actually means, and the fact that, right or wrong, not all speech is allowed in public.
> Nowhere does [the first amendment] preface this with a statement like “the freedom of speech shall be defined as...”
That is correct, but it does start with the words “Congress shall make no laws...” which is an uber-law defining the idea that speech will have legal protection. Those five words are a constitutional directive that defines what “freedom” means in the term “freedom of speech” in the United States.
> My argument is that freedom of speech is a universal right
The principle of freedom of speech is the idea that most speech should be a universal right; that principle does not allow for all speech, and it is not universally recognized, therefore is is not a universal "right". It becomes a right and a freedom when the principle is recognized and protected by your government.
Freedom of speech is an explicitly stated goal for the US constitution, and also for the Universal Declaration of Human Rights. Those documents are not recognized in all countries, and both documents have exceptions. In no case is there a blanket protection for any speech at all, anywhere in the world today.
> One of the most power uses for freedom of speech (and freedom of the press) is criticizing governments and powerful entities.
Again, you seem to have the misconception that “freedom of speech” is a term that is referring to speech that takes a moral stand against power or against the law. What you’re talking about is “speech”, not the principle of “freedom of speech”, nor the legal protections we call “freedom of speech”. If you might be sent to jail for saying it, then you aren’t enjoying freedom. The better term for this is “speaking to power”.
You seem to be referring to cases where people should have freedom of speech in principle, but don’t. The term “freedom of speech” is the term for the idea that most speech should or will be protected and allowed by law. That’s what the word “freedom” is referring to.
> But what does freedom of speech even mean if the only criticism or forms of expression allowed are those permitted by the government?
What would freedom of speech even mean if it's not permitted by the government?
In the US, freedom of speech means that a journalist is allowed to criticize the president’s public policy actions and not be sent to jail, for example. People are allowed to protest in public.
In China, journalists who criticize the legitimacy of the communist party are put in jail. In China, you are not allowed to use Facebook or Google, and people are jailed for attending public protests.
If you want to understand what our government means by speech that is permitted and protected by the government, you just have to look at other countries that don’t recognize those freedoms.