It's allowed to have more than one protagonist and more than one antagonist in a story.
The protagonist is often the main character, often who the readers gets as a viewpoint character. The antagonist is the one who is at cross purposes for the protagonist.

Jim Butcher's Calderon series has two protagonists: Tavi and Amara. It has many antagonists who are against it.

So what if you called each of your three leads a protagonist. Who is against them? Why?