There is no such thing as a "natural right of freedom of speech". If one sovereign in the history of mankind decides to allow unrestricted freedom of speech in its constitution, it is just that: an episode in the history of legal systems established by humans. It can turn out as a bad idea, or a milestone for better societies. We will see. In no way is it a "natural right". Not even would it be a natural right, if it was mentioned in the bible as one of the 10 commandments from god (disregarding the FACT, that there are some serious restrictions of freedom of speech in that: "Thou shalt not bear false witness against thy neighbour").
In fact, there is no such thing as a natural right at all. Rights are derived from value systems, and the choice of value system is mostly based on aesthetics. There is no way to say whether the Western Christianity-based value system is "better" than, say, the Confucian value system, because the word "better" cannot be defined from first principles (without invoking a particular value system).
The most obvious first principle is that a better value system should keep you alive. Being alive is foundational.
From that you can derive other principles, like value systems should result in the production of food, clean water, protection against wild animals and invaders, disease, etc.
From that you can derive yet more principles, like the value of efficient resource allocation, stable governance and so on.
And judged by basic things like "is this set of cultural values good at keeping people alive and healthy" you can quickly conclude that some are better than others, objectively so.
To deny this is to argue that wishing to be alive rather than dead is merely an aesthetic preference - an absurd starting point, lacking any intellectual merit.
You're perfectly entitled to feel that certain rights should be universal and inalienable. It's also clear that nobody agrees on what those rights are, and that they get violated all the time.
