Cannibalism is of the table, as it violates God's law, so we have symbolic meaning.
At the Last Supper, He didn't roast His body and command all of it be eaten. He rather gave them bread and wine. He gave them bread and wine, and that is so clearly spelled out, there can be no questioning of it. Bread and wine.
Also, looking back at the first passover, it was the painting of blood on the doorpost which was salvific, not the eating of the lamb. The death angel passed over homes where the blood was on the door frames.
We don't literally paint Christ's blood on our doorways. We don't literally eat His flesh, and we don't literally drink blood. Circumcision was symbolic. Baptism is symbolic. . . It's all symbolic. Taking up our cross is symbolic. I could go on if you need more.
No, far be it from me to have to ask any Christian to imagine Jesus doing a miracle. Oh wait.
So since it does not say Jesus performed a miracle, did they leave out the part of the story where they told the boy to run back to town and get wagon loads of more bread and fish for Jesus to break up into pieces to sustain the faithful?

Gee maybe it is about sustaining Christian faith by having God's Grace applied in a very special way. A way that has nothing to do with needing to eat human flesh and drink human blood for nutritional support. It is a spiritual food for an application of Supernatural Grace to help sustain our faith.
From the 6th chapter of the Gospel of Love (shortened and my bolding added):
Jesus answered them, "Truly, truly, I say to you, you seek me, not because you saw signs, but because you ate your fill of the loaves. Do not labor for the food which perishes, but for the food which endures to eternal life, which the Son of man will give to you; for on him has God the Father set his seal."
"Our fathers ate the manna in the wilderness; as it is written, 'He gave them bread from heaven to eat.""
Jesus then said to them, "Truly, truly, I say to you, it was not Moses who gave you the bread from heaven; my Father gives you the true bread from heaven. For the bread of God is that which comes down from heaven, and gives life to the world."
They said to him, "Lord, give us this bread always."
Jesus said to them, "I am the bread of life; he who comes to me shall not hunger, and he who believes in me shall never thirst.
The Jews then murmured at him, because he said, "I am the bread which came down from heaven.
Truly, truly, I say to you, he who believes has eternal life. I am the bread of life. Your fathers ate the manna in the wilderness, and they died. This is the bread which comes down from heaven, that a man may eat of it and not die. I am the living bread which came down from heaven; if any one eats of this bread, he will live for ever; and the bread which I shall give for the life of the world is my flesh."
The Jews then disputed among themselves, saying, "How can this man give us his flesh to eat?
So Jesus said to them, "Truly, truly, I say to you, unless you eat the flesh of the Son of man and drink his blood, you have no life in you; he who eats my flesh and drinks my blood has eternal life, and I will raise him up at the last day. For my flesh is food indeed, and my blood is drink indeed. He who eats my flesh and drinks my blood abides in me, and I in him.
As the living Father sent me, and I live because of the Father, so he who eats me will live because of me. This is the bread which came down from heaven, not such as the fathers ate and died; he who eats this bread will live for ever."
Many of his disciples, when they heard it, said, "This is a hard saying; who can listen to it?"
But Jesus, knowing in himself that his disciples murmured at it, said to them, "Do you take offense at this?
After this many of his disciples drew back and no longer went about with him.
Jesus said to the twelve, "Do you also wish to go away?"
Simon Peter answered him, "Lord, to whom shall we go? You have the words of eternal life; and we have believed, and have come to know, that you are the Holy One of God."