What factors led to the overwhelmingly high mortality rate among the early jamestown colonists

Lack of incentive - The lack of incentive among the colonists to complete important tasks led to the tasks not getting done. Many settlers were "gentlemanly" - Since most of the settlers considered themselves "gentlemanly", they considered the hard work of a settler "beneath" them and consequently did not get most of the basic things needed to survive done.
Expectations of finding gold - The expectations of finding gold (and mining it) led to people neglecting things such as gathering food, setting up shelter, etc. Location - The location that the settlers chose to settle in at was great for defending against naval incursions but terrible for living conditions. Bad Relations with Natives- The relations with the local Native Americans(which were all mistakenly grouped up into the Powhatan Indians) were not as good as they could be; if they had had a better relationship they could have traded for food and/or shelter which could have led to lower mortality rates