If Hitler came to power, let's say in an election but it doesn't matter since the right to vote is also a privilege according to your view, and said "alright, henceforth, all blacks lose the privilege of living", would you find that irrefutable and in conformity with your own logic? If Jeffrey Epstein took power and said "children may now be raped at will", is that a matter of a privilege being cancelled? Does "might make right" however you define "might"?
I certainly hope not.
Practically, however, these rights are only inalienable as long as the powers-that-be (police, military, organs of the state) agree -- if hypothetical Emperor Epstein (or real-life President Ashraf Ghani) declares child rape to be legal, and police and courts obey him, then good luck going up against them...
The definition you used is about what's morally right and in that sense talking about fundamental rights that can't be taken away if you want to hold up some definition of human dignity makes sense, but even then it's subjective to some degree and depends on which school of thought you subscribe to.
Your example shows exactly this ditchomy. If freedom can be taken away and sexual consent ignored, those things can't be at fundamental or real as physical laws. But even so I have a hard time imagining most who see it this way would consider this as anything but reprehensible.
A right by its name can be given or taken away. I feel the discussion about fundamental rights is moot as it always depends on the powers that be. In that sense I prefer dane-pgp's explanation of these being more foundational rights.
Your thoughts and beliefs and your actions are what you are and not a right.