>In my experience "agile" was a loose rebranding of ideas that had been around for a long while (see all the other non-waterfall approaches that predate it) and "Agile" (i.e. the manifesto) was just one attempt at one of these sort of methodologies.

You are correct. The Agile term was probably marketed to the management types as a some breakthrough methodology to _finally_ control the budget for software development. Then it took a life of it's own as many things do.