Freedom of speech is protected only so much as the protection is enforced. It is not some sort of fundamental law. With weak-kneed politicians and indifferent population it inevitably erodes.
"ARTICLE 10 Freedom of expression 1. Everyone has the right to freedom of expression. This right shall include freedom to hold opinions and to receive and impart information and ideas without interference by public authority and regardless of frontiers. This Article shall not prevent States from requiring the licensing of broadcasting, television or cinema enterprises. 2. The exercise of these freedoms, since it carries with it duties and responsibilities, may be subject to such formalities, conditions, restrictions or penalties as are prescribed by law and are necessary in a democratic society, in the interests of national security, territorial integrity or public safety, for the prevention of disorder or crime, for the protection of health or morals, for the protection of the reputation or rights of others, for preventing the disclosure of information received in confidence, or for maintaining the authority and impartiality of the judiciary."
It is not a fundamental law in scientific sense, i.e. it is not a natural property of any kind. You want freedom of speech, fine, but you have to fight to get it and keep it alive. Otherwise it becomes just another unenforceable legalistic quirk like beheading for insulting the Queen is today.
This needs to be said more often… rights cannot be reduced to a “declaration” or a “bill”. They are social constructs that wither away and die without constant social reinforcement, both formal and informal.
But, given that, natural rights can be violated and fail to be protected from those who would do so. So just because something is natural in nature does not mean it cannot be suppressed. It is natural and proper for human beings to speak, but speech can be suppressed. So yes, a society that stops protecting rights will see more violations of them. Declarations are magic incantations. You need power and authority to back them up.
(Also, w.r.t. freedom of speech, I am here not assuming unrestricted speech and "expression"; this has never existed and cannot exist and so on. Rights are not absolute: you can forfeit even your right to life by murdering another human being, for example. Thus rights must be understood in the context of justice.)
Are you saying that you have achieved perfect understanding of this? I think that implies a sophistication way beyond were we are as a species today.
"Article 36. Citizens of the People's Republic of China enjoy freedom of religious belief..."
"Article 37. The freedom of person of citizens of the People's Republic of China is inviolable..."
"Article 49. Marriage, the family, and mother and child are protected by the state..."
Just meaningless words on a page. To be completely fair, the text does imply that the above isn't worth a wooden nickel in practice:
"Article 51. The exercise by citizens of the People's Republic of China of their freedoms and rights may not infringe upon the interests of the state, of society and of the collective, or upon the lawful freedoms and rights of other citizens."
The European Convention on Human Rights has a similar clause (which you quoted) that allows the state to eliminate one's rights "for the protection of health or morals". It seems that "human rights" are mainly there to make the state seem legitimate. They "protect" humans against the state for exactly as long as the state allows.