Self-defence is a right, exercisable under certain well-defined circumstances.
The circumstances are not well-defined. This is misleading. The principles are well-defined but broadly applicable to a wide range of not defined situations.
But it is not a fundamental human right, because fundamental human rights are inalienable. The fact that people do not have a right to defend themselves in all circumstances means that the right is not a fundamental one.
Freedom of movement within a state can be restricted. Parolees, for example.
Presumption of innocence - only in court. Police can determine guilt for all practical purposed and shoot certain people. In fact, the rest of us can.
Freedom from being treated in a degrading manner is also limited. Being asked to dress like a chicken and hand out fliers, for example.
Free speech can be limited by courts (gag orders), public safety concerns, national security issues, and by contract - and a lot of coercion can go into those contracts. The Insider is a great film about how one's freedom of speech can be limited. Sure, he did speak in the end, and lost his family, health and a lot of time in the process.
Rights to assemble are limited all the time by courts, local governments and police.
I think the fact that it is not included in the Bill of Rights is that it is even more obvious than the principles set forth there. EVERY culture and country in the world allows self-defensive actions in relation to the violence of others. It is more fundamental. What the Bill of rights was doing was extending the realms of rights. The court system in the US for example has always recognized the right to self-defense. It has moved the boundaries around, but this is also true for freedom of speech. Public safety concerns, slander, even noise regulations and laws around incitement to riot can be seen as limitations on this right. Further every company in the US will restrict the freedom of speech of its employees and many of these restrictions will be upheld by the courts: company intellectual properties, internal documents can be off limits, expressing opinions about employers, the company, the products and services, especially in public forums can be punished by the company, often without legal redress.
You can't lose an inalienable, fundamental right. To prevent a person from exercising a fundamental human right is (or ought to be) a crime.
You cannot lose the right to self-defense. It can be decided that you were not acting in self-defense. You were the aggressor. You actions included attack or a raise in the level of aggression. You could have defended yourself better by running away. You can also be judged to have hallucinated a threat. But none of these judgements take away from the fact that you have the right to defend yourself against physical attack.
Again, do you really think someone being raped does not have the right to physically hurt her attacker?