The OT Lord’s Supper, the NT Passover
The Supper that Jesus instituted on the night he was betrayed was a new Passover meal. Or we might say that the Passover was the Old Testament Lord’s Supper.
The reason the Lord instituted the Passover was so that people of Israel would always remember and proclaim their redemption from Egypt:
This day shall be for you a memorial day, and you shall keep it as a feast to the Lord; throughout your generations, as a statute forever, you shall keep it as a feast. (Exodus 12:14)
And when you come to the land that the Lord will give you, as he has promised, you shall keep this service. And when your children say to you, ‘What do you mean by this service?’ you shall say, ‘It is the sacrifice of the Lord's Passover, for he passed over the houses of the people of Israel in Egypt, when he struck the Egyptians but spared our houses.’” (Exodus 12:25-27)
The Lord’s Supper was instituted for the same reason:
For I received from the Lord what I also delivered to you, that the Lord Jesus on the night when he was betrayed took bread, and when he had given thanks, he broke it, and said, “This is my body which is for you. Do this in remembrance of me.” In the same way also he took the cup, after supper, saying, “This cup is the new covenant in my blood. Do this, as often as you drink it, in remembrance of me.” For as often as you eat this bread and drink the cup, you proclaim the Lord's death until he comes. (1 Corinthians 11:23-26)
OT Israel looked back to the Exodus through the Passover meal. NT Israel (that's us) looks back to the cross and resurrection of Jesus through the Lord’s Supper.
As often as we eat this new Passover meal we remember a greater exodus: "for he has delivered us from the domain of darkness and translated us into the kingdom of his beloved Son, in whom we have redemption, the forgiveness of sin."