You bring up some good points. To expand on the idea of anmensis, and the Last Supper. People who have been here for a long time know that I was raised in a Jewish home, and my family escaped the Shoah because of the intervention of Pope Pius XII, and Cardinal Rancolli, (later Pope John XIII). As part of that intervention my grandparents and other relatives were not required or in any way encouraged to convert to the Catholic Faith, except by the example of Christ’s love. So when I was first presented with the Eucharist and the truth that it is Jesus Himself, and not just a symbol or memorial it was not at all hard to believe.
Jesus chose (and I believe that He did so for a very important reason) the feast of Passover for the insitution of the Last Supper, and for His sacrifice on the cross.
At the Seder we are taught that we are to make Anmensis, of the Exodus. Now don’t forget that at the time of Jesus, many Jews living outside of Israel did not speak much Hebrew. The situation was such that the Septuagent a Greek translation of the OT and several of the books of the OT (Tobit, Sirach, Maccabees (I and II) and a few others were originally written in Greek. At the Seder, the ritual meal eaten at Passover all Jews are taught as part of the rite that “We do not say that God did these wonders at that place, or for those people.” We are taught by the Rabbis, and Jesus and His Apostles in following the ritual understood that by participating in the rite we too should consider that we came out of the land of Egypt, that we participate in the Exodus. Now this was not a symbolic Exodus, but by participating in the Seder, by God’s power we mytically, and in a real sense must consider that we are participating in the Exodus. Anmensis is not just a recalling of a past event, but making an event present again.
So too with the Mass, God, in the second person of the Trinity makes the effects of Calvary present, and transends time to be on the altar with us. We don’t simply symbolically stand at Calvary, but Calvary and all the graces Jesus gives us are made present by Him through the ministry of His priest. The priest acts in person Christi, because Jesus works through the Ministry of the priesthood which Jesus shares with the Church by Apostolic Succession to individual priests. It is Jesus’ priesthood that He shares with us, and it is Jesus who through the ministry of His priests that supplies all the Graces that Jesus Himself imparts through those same Sacraments that He instituted.