Actually no. Alolan lore considers the island guardians to be blessed by the legendaries. They are, in other words, the chosen ones, much akin to the Aura Guardians of Sinnohan legend and the chosen of Ho-oh of Johto’s … only, well, they’re pokémon. And also immortal apparently.
Strangely, though, unlike in other regions, the Alolan natives rank the guardians higher in terms of things to worship than legends; that is, they worship the guardians the way people from elsewhere may worship Ho-oh or Arceus or so forth. It’s possible this is because of a lack of named legendaries in Alolan tradition (legendaries to them are implied to be packages of primordial chaos) or because the story goes that the guardians are direct protectors of humanity, but regardless of the reason, almost all rituals are dedicated to the guardians, rather than the legendaries that blessed them.
The Pokédex According to Bill 