Actor and Director and Producer would be more than enough for everybody. Especially combined with several Oscar wins as director and producer, and even Oscar nominations as actor (on top of iconic roles).
But he has also been an OST composer for some films.
The point is a Homer or Twain, etc, were original authors of works and Eastwood was not an author of any of those works. If an unknown actor portrayed the lead in a Huckleberry Finn film, that would not elevate that actor to the level of a Mark Twain as an author.
But as a director, they could be elevated to the status of creator, and perhaps directing is the truer American art form rather than ...epic poetry or the novel. Which speaks to the core of the question at a different level.
Besides, Homer didn't write his own plots either, he adapted original screenplays, so to speak!
But he has also been an OST composer for some films.