The Last Supper took place during a Passover meal. Recall that the original Passover meal centered on an unblemished lamb whose blood was shed to save Israel from death during the Passover of the Angel that night. Each year, on God’s instructions, the Jews observed a Passover meal in memory of the original Passover events. To the Jews, the Passover celebration was (and is) more than a mere memorial—or calling to mind—but somehow a participation in the original Passover. Thus we have three realities: the original Passover supper, the Passover event, and every subsequent annual Passover commemorative meal.
Now, Christ shared with his Apostles a new Passover meal in which he said he was giving them his body and blood to eat and drink. Beginning that evening and continuing the next day in his Passion, Christ offered himself as the unblemished Lamb of God, sacrificing himself for the salvation of the entire world. At the Last Supper Christ also instructed them to “Do this in remembrance of me” (Lk 22:19), which they faithfully did. Thus we also have three realities: the Last Supper, the Passion, and every subsequent Eucharistic sacrifice.
The original Passover meal and the Last Supper are in parallel.
The deadly Passover event and the bloody Passion are in parallel.
Every Passover Seder and every subsequent Mass are in parallel.