What are the two main ideas that are talked about in chapter two in 1491?

The first main idea Mann presents is that the first English settlement in New England, Plymouth, grew out of a much more complex set of circumstances than most present-day Americans are taught in school. Mann asserts that the Indians were not helpless victims or a perfect society, but rather a people who had a hand in their own destiny, like all other peoples throughout history. He tells the story of Tisquantum and Massasoit and explains that one reason the Wampanoag welcomed the pilgrims was to ally with them against the Narraganset.
Another idea Mann presents is that disease spreading through the Indian villages and the political vacuum that it caused were much bigger factors than European technological advances. Disease was the main reason the colonists were successful in eventually gaining a foothold in New England. The colonists and Indians alike would not have understood how diseases are spread so it was attributed to spiritual forces.