lack of antibodies from previous exposure and a lack of experience in treating unfamiliar diseases.
Everywhere, indigenous peoples lost the information and technology in the minds of the people who died, and often their social and political structures were shattered.
From the Spanish perspective epidemics were a mixed blessing. They reduced resistance to colonization, but they also destroyed the work force the colonizers needed to exploit their new possessions.
Colonizers in New England would assume that their god had sent the epidemics to clear the land for the use of the colonizers.