I have understood that like the strong Greek anamnesis, the 'rememberance' of the orginal Passover each Pesach is understood as an actual participation in the original.
So the anamnesis of Christ in the Eucharist which He told us is His Body and His Blood is an actual participation, not simply a recalling to mind.
Were that the case, we would fear the angel of death taking our firstborn. It is a memorial, and a remembrance of the past. In doing so, we form a unity in action with the people of Israel who have observed Passover through the ages. But it is not a unity of time: we do not believe that we are somehow reliving or literally "making-present" the events of the first Passover in Egypt.