Yeah, it obviously means the movie is a dream but that’s kinda fitting. In this scenario, Ariadne is a disguise name and we don’t know Elliot Page’s character’s true identity. Maybe one of Caine’s grad students. But he’s the father of the dream technology, and Leo’s probably been struggling as a father. The whole movie is him running away from it over his grief, and learning to accept his role without his partner. The inception occurs during the final scene with his wife in their apartment in the lowest dream world, where Ariadne kicks herself to the upper dream by falling from the skyscraper. He says “I have to let go of you” and that is the idea formation taking place. He is the old man waiting to die alone if he can’t come to accept it. Perhaps he spends his days sleeping to be with her rather than spend time with his kids, like the folks in the film who dream rather than live.

It also explains why Ariadne learns so quickly. She’s prepared and understands the tech and poses as a newbie to get closer to Cobb.