Real human rights entail human obligations. But not all human obligations to treat other humans well entail identifiable human rights.
The right to life obligates others not to murder; the right to liberty obligates others not to enslave, but the obligation to be kind or helpful or charitable does not give an individual a claim on me for not giving to him or her. (At least not a legally enforceable one.)
I have an obligation to help others… but who determines how much of my resources should be devoted to providing for my family, starting endeavors by which I hope to gain more resources or guarding against future disaster? All those subjective calculations are involved in real decisions about how and when to help someone. Human rights derive from objective and relatively invariant and universally similar obligations on all people. Obligations that depend on judgments about circumstances can’t generate rights.
That doesn’t mean these obligations aren’t real. But it does suggest that enforcing these obligations by invoking “rights” is a subterfuge.