There is absolutely no purpose in having mere symbolism in the discourse on the bread of life in John 6, the Last Supper, or Corinthians chapters 10 and 11.
We can remember the crucifixion by way of the crucifixion accounts as well as other areas of the NT letters. We do not need the Last Supper meal for that purpose. The intent and purpose of the words “This is my body” and “This is my Blood” is quite clear.
Literal or symbolic and why? It is literal because Jesus said it was in the discourse on the bread of life. It is literal because it is necessary for us. It is necessary for us because Jesus says it is.
Jesus says it is in John 6:53-54 which reads as follows:
"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.”
And how do we know it is literal? We know it is literal because Jesus says that his flesh and blood are true food and true drink four different times during the discourse and he uses progressively stronger language as he goes along. In the Greek Jesus starts with the word “phago” which literally means “to eat.” He then continues with the word “trogo” which means to “gnaw or to chew.” The latter usage makes it more graphic and literal to remove any lingering doubts as to his intention.
Likewise, Jesus says that the bread that he will give us to eat is the same flesh that will hang upon the cross. We see this in John 6:51 where it says:
“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.”
If the bread that Jesus says is his flesh is symbolic, than his flesh that hung upon the cross must also be symbolic. There is nothing about the discourse on the bread of life that logically points to a symbolic understanding. Jesus was clear in the discourse and he was clear at the Last Supper. Likewise, Paul is clear in 1 Corinthians chapters 10 and 11. Likewise, all of the early Christian writers were clear on the issue as well.
Ignatius of Antioch, who was ordained by the apostle John, wrote in his letter to the Church at Smyrna the following:
“They abstain from the Eucharist and from prayer, because they confess not the Eucharist to be the flesh of our Savior Jesus Christ, which suffered for our sins,and which the Father, of His goodness, raised up again. Those, therefore, who speak against this gift of God, incur death in the midst of their disputes.”
I hope this helps.