Once the Virginia Company realized that growing tobacco would generate the quickests profits from a colony in Virgnia, the investors sought to stimulate populaton growth to increase the supply of farm laborers and planters. To recruit people with enough wealth to start a new farm, the Virginia Company offered free land to anyone who imported new residents into Virginia. The headrights system provided 50 acres for each new resident.
There were people in England willing to take a chance at creating a better life across the Atlantic Ocean. They were recruited with the promise of a free ride on a ship to Virginia, and fre housing and food for seven or more years, in exchange for working for free during that period of indenture.
Source: Timeline, Indentured Servants vs. Slaves in Jamestown, Virginia 1607-1619 Indentured Servitude versus Slavery
Source: Indentured Servitude and the Origins of Slavery at Jamestown