It is unclear who was the first Jewish student at William and Mary.
A 1932 list of students and their faiths indicates that there were 95 "Hebrew" students. ("Religious Preferences," University Archives Subject File Collection) See also The College of William and Mary: A History, notes p. 725.
Samuel Myers (1790-1829) attended William and Mary in 1808-1809. He was a lawyer in Norfolk and Pensacola, Florida, and the son of Moses Myers. There are two collections of papers from the Myers family in the Special Collections Research Center and one includes correspondence with Jewish merchants in Richmond and other cities (see Meyers Papers and Samuel Meyers Papers).