You pose an interesting philosophical exercise. At the heart of your question is: how can people possibly believe that certain concepts could be considered rights?
But if you think about it, the freedoms enumerated in the US and English Bills of Rights weren't always considered rights. If they had been, there would be no need to codify them. At some point, they became
rights in the minds of those that desired them. Freedom of Speech in England wasn't codified until 1689; 100 years before the US Bill of Rights. Was that when freedom of speech became a right? Or is that when a critical mass of the populace decided to claim
an existing but unrecognized right?
Think about the deeper meaning of the phrase in the Declaration of Independence:
We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable rights, that among these are life, liberty and the pursuit of happiness. That to secure these rights, governments are instituted among men, deriving their just powers from the consent of the governed.
The DoI implies that certain rights exist as a natural consequence of human nature and culture (or Creator, if that is the part of human culture you wish to credit). The meaning is clear: whether the powers that be agree or not, men have certain freedoms. If the PTB do not agree, it is the responsibility of the governed to establish a government that does
recognize those rights. The rights recognized will be established by those that institute the government - the ones that want the rights to be recognized. Or, We The People.
So...if a critical mass of the population in America decides that housing and health care are basic rights, then they are. Just as the English people rose up and claimed their right to free speech 331 years ago, Americans at some point in the future may rise up to claim what they see to be their right to affordable adequate medical care.
Also, be careful when you talk about material possessions as rights that you aren't confusing them with the concepts that those possessions represent. Take housing, for example. The right to housing isn't necessarily a right to possess a house or own a building. It means much more than that. It symbolizes a right to safety, security, roots, heritage, a sense of self and of self-worth. Taken as an aggregate, a sense of community and of belonging. Not really materialistic, wouldn't you say?