What was the primary challenge faced by the Jamestown colonists during the first few years

The settlers arrived to Jamestown, the first permanent English settlement in North America, on 1607. There they faced a lot of difficulties which lead to the death of around 80%-90% of them by 1610. The most notorious problem was their lack of ability to addapt to the new territory, they were not able to gather enough food to survive. The settlers were locked up in the fort, if they got out they could be attacked by the Powhatan Indians which hunting lands were being occupied.

As the settlers drank contaminated water they started getting ill. In the winter of 1609-1610, they faced a severe drought, the "Starving time" there a lot of them died of hunger and diseases.