What were the most difficult challenges faced by the Plymouth and jamestowm settlers?

The reason that the first settlers of Plymoth were struggling because they came over to the Americas in a very small ship called the mayflower. When the settlers arrived they could not find land to clear and build they settlement. While they were waiting to build they were all packed in the mayflower and started to become ill and dying. So right then weeks later they found a land cleared by a deceased Indian tribe. They built there settlement and found an Indian Somoset, Who introduce crops and farming and they got together to have a dinner (Thanksgiving).