Historians generally regard historical knowledge as conditional: the claim to truth means merely that historians have some good reason in the form of evidence for believing in the validity of their accounts. New evidence or a reinterpretation of existing evidence can completely change a historian's conclusions. Based on available evidence, it appears there was indeed cannibalism at Jamestown during the so-called "starving time" in 1609-10.
In 2012, archaeologists found the skull and leg bone of a teenage girl, whom they called "Jane," together with animal bones and food remains. Forensic analysis suggested that there had been multiple blows to the skull and that tissue had been cut from the bone. The lead archaeologist concluded that "Jane" was clearly cannibalized. The first link below provides a more detailed explanation of the evidence together with a short video.
This forensic evidence supports the written claims by prominent Jamestown settlers George Percy (1580-1627) and John Smith (1580-1631) that cannibalism took place. Some other contemporaries denied that cannibalism ever took place. In order to interpret this evidence in its full context, one would want to study the early history of the Jamestown colony, including the "starving time," and cannibalism in colonial America.