They should have called this movie Clint Eastwood and a Monkey. That's a movie anyone would watch, no matter the real premise. A slap-sticky action-comedy probably makes the most sense, but if this were a spaghetti western, family drama, or slasher, we'd still watch. Just so long as the Man With No Name got into wild adventures with a primate.
Apparently, numerous advisers recommended Eastwood not make this movie. Clint knew better. When adjusted for inflation, this film is one of the top 200 hundred highest grossing films of all time. And all with a title that turns non-native speakers of English into spasming heaps of confusion.