We'd like to discuss the deep significance of this title, and how it invests the film with all kinds of subtle nuance and meaning…but that would be a lie.
They're cutting to the chase as quickly as they can here. It's called Thor because it's about a god named Thor. Ta-da!
When coupled with the simple-to-the-point-of-ridiculousness poster—a close-up of Hemsworth's face in red—it adds up to a get-to-the-point title that wants to get on with the business of superhero-ing as quickly as possible.