This is more inquiry than commentary. Interested to see what people think.
The idea of human rights as myth, in my estimation, is really about using them in a myth-making manner. They are ideals to strive for, and protect. Basic moral goods that apply universally, and from which other 'rights' (perhaps better defined as legal rights) or duties may grow from.
I'd had a conversation about universal human rights with a Progressive who considers them to be a myth or social construct. Only useful or meaningful if they are enforced. I took a different view. I feel they are real things, existing as useful concepts whether they are enforced or not. In fact, I pointed out, enforcing them is the incorrect term. Protecting them, or efficiently allowing their application, is more to the point. But even if they are not protected or applied, they are real nonetheless. Which is why so many people have fought for them over the years, and why nations which do apply them efficiently see so many wonderful benefits to their society.
His next question was "what makes them real? How can you justify a right to a free attorney but not a right to free medical care?" I replied that was a logical fallacy. There is no right to a free attorney, that's just a SCOTUS ruling. That has no bearing on this discussion (though I'm open to other ideas that you may have in comments).
So what are basic human rights? To me, they are real things. Things you are endowed with at no cost, upon birth. The right to free speech, for example. The right to associate with whomever you like. The right to believe what you want. The right to worship as you see fit. These cost nothing. They do not impact others' rights, or other people (physically or directly) in any limiting fashion. What are typically known as "Natural Rights" - a thing Progressives don't believe in because, to them, everything is a social construct and open to manipulation.