I don't think the UN is the ultimate arbiter of what is or is not a right. Not that something being a "right" really means anything unless you have a way to enforce it.
At the time of this Universal Declaration of Human Rights being published, the UN had 54 member countries[0]. Not sure what organization in human history is better positioned to author such a declaration.
Further, nitpicking around the definition of "rights", or who is worthy of declaring them has zero relevance to the point I'm making - that health care is traditionally an element of human rights policies and/or has a deep connection to the subject of human rights.
