Jemma Simmons was a virtual recreation of the real-world person of the same name inside the Framework.
Jemma Simmons was a S.H.I.E.L.D. agent shot and killed during the Massacre at the S.H.I.E.L.D. Academy.
Several years after Simmons was buried in an open grave with her deceased colleagues, her real-world counterpart logged into the Framework and took her place.