I don't believe there are any natural, inherent, or "univeral" rights. There is no right of self-ownership. It's just a social construct, albeit a useful one for opposing authoritarianism and for facilitating liberty.
This eaglitarian notion of inherent, natural, universal rights that pertain to each person merely because they exist, especially the so-called right of self-ownership, cherished by romantics and moralists of all stripes, is the primary underpinning of the Georgist's theories. And well do I recognize that it is also the underpinning of most Libertarian thought and arguments.
But it is an artificially constructed notion. It is true only to the extent that we voluntarily subscribe to it. There is only nature. We are a part of it, just like every nutria, amoeba, or broccoli. The fact that we exist in the natural universe affords us an opportunity to survive. Not the right to survive, or to prosper, just an opportunity. Mere existence guarantees us nothing, grants us ownership of nothing, nor obligates nature or our fellow man to gift us with anything.
No one has the right to *be*, and therefore, no one has the right to *be* somewhere.
Is the value of an individual's life to that person a "social construct?"
For the most part, in modern western society at least, probably not, but it is socially constructed to one degree or another.
A person's view of self and the value he attaches to his own life is inevitably informed to some degree by the society in which his world view is shaped. There are countless examples throughout history of people born into slave or servant castes who expend their lives to protect, honor, or amuse the high-born of the ruling caste. It seems likely that a large portion of the perceived value of the lives of such people, slaves, servants, and rulers, is socially constructed.
So I'd say there is a component of self-value that is socially constructed. The degree of influence varies from person to person, and from society to society. The more one studies philosophy and society and history, the more one's views may diverge from accepted norms of ones society.
This has nothing to do with the proposition that universal, inherent, unalienable rights exist.