A musicologist may drop by, IB, and confirm that pop evolved from American religious music; and rock from American blues and country, etc.

I think first of all your musicologist would confirm that American religious music & American blues and country evolved from the music of the African, British & European migrants (willing or otherwise) who brought it with them as part of their respective cultural identities, which is why I say these things are part of an ongoing process of musical & cultural coalescence of vast complexity and not an aspect of the globalisation you are rightly wary of.