Why most of Americans people are not called native Americans?

Because most Americans aren't native, They came over from England(hence the term New England) to escape the churches. The people that were here before Europeans are considered Native because they inhabited America before almost anyone else. Everyone else that is an American came from all over the world. Since the founding fathers wanted this country to be a mix of all origins anyone that resides here is classified as an American.

All of the non-native Americans did not come over from England only, they came from all over Europe and later on Asia and Latin America and they came over for a variety of reasons not just to escape the church, they also came for land, economic reasons, political reason etc.

Native Americans are those who are descendants of the first people in America. Though most Americans are, in fact, native to the land by birth, most Americans ancestors were not native to the land, thus they aren't called Native Americans.