Doesn't Paul think that Jesus was probably buried in common grave like most criminals.

Not when you look at that four line formula in I Corinthians 15!  It is like an outline of the events of the death of Jesus, the burial by Joseph of Arimathea, the empty tomb, and then the appearance narratives. Compared to
the Acts of the Apostles on the one hand and the Gospels on the other hand, this summary in I Corinthians 15 is like an outline, which includes as the second line Joseph’s burial of Jesus in the tomb (WLC).