The phrase 'human rights' is a bit like the phrase 'social justice': both are overused and ideologically charged.
Adrian McKinty recently (and somewhat anachronistically) referred to Roger Casement (1864-1916) as a 'champion of human rights'.
Although the term 'human rights' was not widely used until relatively recently, I recognize that the general concept has been around for centuries. My understanding is that the modern idea evolved from the medieval tradition of natural law. The notion of a divinely sanctioned moral order lying behind (and somehow justifying) human-made laws and legal systems led to the notion of universal rights which came to prominence in the 18th century. The concept was initially applied to individuals but was broadened during the Romantic period and beyond to encompass the rights of ethnic groups (or nations) to self-determination, etc. Roger Casement's anti-colonialism and (militant) Irish nationalism grew out of this tradition of thought, so McKinty's description is not altogether wrong.
But I do have problems with the term itself, as I don't think most of the people who use it realize what (in my view at any rate) its use is committing them to - that is, what assumptions it depends on to be meaningful.
It seems to me that the term 'human rights' only makes sense a) if you believe in an objectively existing natural law (or immaterial moral realm) where these rights are somehow inscribed; and/or b) if you envisage and advocate some kind of comprehensive institutional arrangement (not necessarily a world government) which would list certain rights as universally enforceable laws. (In the latter case, the rights may be seen as transcending the laws, or, if one rejects the natural law idea, merely as legal rights.)
This is not just about terminology. There are deep issues of belief involved. In my view, it's most unfortunate that humanitarian causes etc. have become linked to this (rather problematic) term. Humanitarian goals can be and have been effectively pursued without using the term or appealing to the concept. One can be motivated simply by a sense of human decency, or fairness, or compassion, or empathy, or by other emotions or convictions which owe little or nothing to the concept of universal human rights.