Why did colonists come to Jamestown originally?

There was an opportunity for settlement of North America after James I became king in 1603. England ended its wars with Spain and Scotland, and this enabled the country to invest its money and manpower in new ventures. Joint-stock companies had already been successful in foreign trade. In 1606, James I gave a monopoly to the Virginia Company of London to handle English trade in North America.
The Virginia Company's goal was to make profits in the New World. It planned to achieve this in various ways. First, it wanted to find gold and silver—as the Spanish had previously done in their colonies. Second, the settlers would find a route to the Pacific for trading with the Orient. Third, agricultural products would be shipped back to England. And finally, the settlers planned to convert Indians.
In 1607, 120 men made the voyage and 16 died during the crossing of the Atlantic. The colony struggled, and it was nearly abandoned. The Virginia Company's goals were not reached, and many settlers died. Finally, by 1612, the colony began planting tobacco, and that enabled it to survive.