Primarily the audience. The artist can approach a project with a certain set of ideas, precepts, and motivations, and attempt to communicate something, but the interpretations of the audience supercede that IMO.

That said, different levels of engagement inform different interpretations. For instance, there’re folks who watched Starship Troopers that didn’t understand it was satire until they listened to the director’s commentary. Knowing this does impact an audience’s interpretation when engaging with the work - all of a sudden, certain things lend themselves to closer consideration. But the audience still brings their own experiences, sociocultural context, and ideas to a work of art. Over time, it is the audience’s interpretations that carry on as people share that experience.

Ideally, a work stands on its own without reference to paratext/the creator’s claims. But those can play a part in informing your own interpretation.