My main concern is still the Eucharist. If all of Jesus’ quotes were compiled into a poster, and you threw a dart at the poster, it would be very difficult, probabilistically, to hit a quote that was not metaphor. Why interpret those quotes of His with respect to the Eucharist so literally, when He in general spoke so metaphorically? What is it that compels Catholics to believe that above all His other words, that those few involving communion are literal, while almost all others are not?
There is so much to cover regarding the intellectual “why” of the Catholic position on Eucharist that it would entail an entire thread of its own. It starts in Genesis (Abraham/Isaac; Melchizedek) and, of course works it’s way through the first Passover and the memorial that came afterwards. I’m guessing, though, based on your NT focus that you are not a Scripture scholar (nor am I) and that perhaps a focus on the NT dimensions of the Eucharist would serve you well.
We cannot, of course ignore the Passover since John the Baptizer

)) in heralding Jesus proclaimed, “Behold the lamb of God who takes away the sins of the world”. It is impossible to understand that reference of Christ as being the “lamb of God” without a basic knowledge of the Passover sacrifice. Very briefly, the Passover lamb was the key to not incurring the Lord’s wrath via the Angel of Death. In order to be “saved” from that one had to: Get an appropriate lamb, slaughter it, spread it’s blood on the doorposts and…eat it. (Ex 12:7-10)
Fast forward to the NT. In what way - or ways - is Christ the “lamb of God who takes away the sins of the world”? It is quite evident to me that He was that lamb in all ways - but, at the same time, different. How so?
I don’t think that we would have too much disagreement on the following points: that Christ was the
appropriate offering, that He was
slaughtered, that his* blood was spread* on a “door post” (ie, the Cross). The point of contention is the question of whether He is
eaten. Lets start with the Nativity scene - consider the following:
Jesus, who is the bread of life, was born in a manger (same root as “mangia” which, in Italian means to eat ) in the town of Bethlehem. And what does Bethlehem mean? House of Bread. So the bread of life was born in the house of bread and placed into a feeding trough. It seems pretty straight forward…eat!
Lets now jump to John 6 where Jesus rocked the boat. The Apostles were all at this exchange. Jesus said, "I am the living bread that came down from heaven; whoever eats this bread will live forever; and the bread that I will give is my flesh for the life of the world.” The Jews quarreled among themselves, saying, “How can this man give us [his] flesh to eat?”, and ultimately left being dissatisfied with the answer that Christ gave. Why? They were not willing to trust him beyond what they understood - beyond their carnal knowledge. His Apostles were no less confused intellectually, but they had not placed their intellect above their trust in the Lord (cf Prov 3:5-6). They held on by faith. And so when asked by our Lord, “Do you also want to leave?” , Simon Peter answered him - expressing the fact that they trusted Him above everything, including their earthly understanding, said: , “Master, to whom shall we go? You have the words of eternal life. We have come to believe and are convinced that you are the Holy One of God.” Their faith in him transcended their inability to understand all that he told them. And there is an important lesson in this for all of us…
Christ
did eventually explain to them what he was talking about in John 6, but it was much later - much like answers to prayer, which often come much later than we wish to receive them. "While they were eating, Jesus took bread, said the blessing, broke it, and giving it to his disciples said, “Take and eat;
this is my body. Then he took a cup, gave thanks, and gave it to them, saying, “Drink from it, all of you, for
this is my blood of the covenant, which will be shed on behalf of many for the forgiveness of sins. " They had never forgotten the John 6 incident and here at the Last Supper they finally got a big piece of the explanation they wanted to . How could they “eat his flesh”? By eating the bread which
is His body. And how could they drink his blood? By drinking the wine that
is His blood. They started to get it, but there’s plenty more to come…