I'd say that Dune, as a single book, is a metaphor for a local Arab community rising up to overthrow a pair of colonial powers (Brits/Harkonnen and American/Atreidis) to take control of their own oil reserves (spice). It is a story about Jihad, a word that is used many times in the books but is notably absent in the latest film. Start changing too many characters and the metaphors to our real world fall apart.
It's about a marginalised community's manipulation by a cynical religious cult, which indoctrinates them to await a messiah, then provides them with that messiah in order to usurp power over their entire society for the cult's own nefarious ends.
That and breeding a super being into existence, which makes the Golden Path necessary. Although, the Bene Gesserit may have thought they were doing all this for the good of human kind. Considering the kind of ossified, medieval structure in place for thousands of years they had to work with.
