Virgin birth, disciples, and resurrection was nothing new. They were part of the qualities that were attributed to most emperors and holy figures in that era, especially the Mithraists which comprised of most the Roman military officers at the time. In other words Constantine's move may have been political in order to gain the allegiance of his officers.
Highly reputable scholars believe that Jesus was never given a proper burial in any tomb from which to rise They think Jesus was dumped into a common pit where, according to one scholar, he was possibly attacked by dogs