In The Giver, some of the archetypes aren't very clear, while others seem to stand out as pretty obvious. The archetype of "the hero" (protagonist) is obviously Jonas. Jonas is an intelligent, and very thoughtful. He possesses strength and courage common in the hero. He is also very brave to be taking the pain of the entire community. These, while typical in a hero, stand out in Jonas and for some reason seem very unique in him.
The Mentor is Again obvious. The giver. It’s actually his job (metaphorically and literally) to be Jonas’s mentor. The giver gives Jonas much needed wisdom and provides insight on their every-day life.
The next two are not so obvious. The shape-shifter I believe doesn’t exist. The bad guy (antagonist), however does. The bad guy in this book is more an idea than a person. The Sameness. When he world decided to make every last thing the same, down to the weather and the hair color of every person alive. When this happened, in a way, every person became the antagonist. Every person became resentful of the way of life Jonas and the giver are trying to create, and until that changes, it might as well be Jonas against the world.