The reality is that marketing is a fundamental part spreading ideas, which is a fundamental part of democracy (and politics in general).

It doesn't really matter if housing as a human right doesn't fit some narrow implied definitions of 18th-century philosophers or statesmen. We live in a different world now, with technology, possibilities, and circumstances that are wildly different. People can no longer simply homestead out on the open land; everything is already owned by someone else, and the cost to buy/rent it is far outpacing the reach of the average person. The deprivation of physical space is a direct threat to a person's livelihood, and this simply wasn't a problem in the age of the manifest destiny.

A new age comes with new problems which require new solutions, which must be implemented by spreading new ideas. Changes occur when a critical mass of people and politicians believe that change is possible and required. So yes, calling it a "right" is marketing, because in a democracy that is how you get things done.

Well I agree marketing is effective. But what's the argument for housing as a human right? You say "It doesn't really matter if housing as a human right doesn't fit some narrow implied definitions of 18th-century philosophers or statesmen." but that doesn't argue why it should be a human right nowadays. Lot's of philosophers and statesmen of today wouldn't agree it is a human right.