The Virginia Company was assigned land in the New World by the king of England. They had high hopes of making a lot of money by growing and making things in their colony that they could ship back to England for a profit. To do this, they needed a labor force.
The Virginia Company advertised for colonists. Anyone who agreed to make the journey was promised 50 acres of land and a share in the profits. That was quite an offer. About 1000 people accepted. A ship set sail for the New World.
Jamestown was the name of the area selected by the Virginia Company to be the new home of these colonists. It was a swampy area, nearly an island, connected to the mainland by a sandbar. It was selected because the Virginia Company believed it could be defended. The colonists were not worried about the natives. The Indians in the area seemed friendly. They were worried about Spanish invasion.
The choice of location did not work out well. The colonists soon ran out of game on the "island", and fresh water was in short supply.
They had other problems. The colonists were badly equipped to start a colony. About half of the colonists had been "gentlemen" back in England. They had little or no work experience. They knew nothing about farming or building. They had no intention of doing any of the work. They expected the others to feed and care for them. As you can imagine, this did not go over well with the other colonists.
Even then, the colonists in Jamestown might have survived if they had had time to plant crops and harvest before winter set in. They did plant. But they were not worried about food. They expected ships to arrive from England. But only a few ships arrived. The ships brought some supplies, but the ships had been sent to take goods back to England, goods that had not yet been created by the colonists.
They might have survived if they had abandoned their original settlement and moved inland where food, water, and firewood were in ample supply. Of course, they did not know if the natives would remain friendly if they moved inland. And the fort they built on the "island" did offer some protection. So they did not move inland.
If it had not been for the generosity of the Indians in the area, they all would have died.
As it was, with only two doctors, low supplies of food and fresh water, freezing temperatures, and almost no medicine to combat disease, only about 100 of the original colonists survived Jamestown.