Who or what is the protagonist in “the colomber” by dino buzzati? the colomber, stefano, the father, or the mother

The word protagonist means the main character in a story. So, here, in "The Colomber," the protagonist is the boy Stefano. The narrator tells us the story of Stefano, his father, and the colomber, which is a shark that's been following Stefano for a while. His father told him that the shark was going to eat him, when in fact it only wanted to give him a pearl and make him rich, which is something he realized when it was too late.