This is a nitpick irrelevant to your point, but still: "the world's oldest democracy" is a meaningless title because who it belongs to depends on the definition of "democracy". I'm sure there's at least half a dozen different places where it is customary to claim the title. See here for data points: https://en.wikipedia.org/wiki/History_of_democracy

I'd say the right way to define "democracy" is not as a system of governance; but rather as a worldview, as an ideology and as an effort.