There is no context in a Jewish feast for someone holding up a piece of bread and saying This is my body.
The context is given in John chapter 6
I am the bread of life
I am the living bread that came down from heaven
.. unless you eat the flesh of the Son of Man and drink his blood, you do not have life within you
. Whoever eats my flesh and drinks my blood has eternal life
.. For my flesh is true food, and my blood is true drink
.
Most of his followers left. They understood he was speaking literally.
Jesus turns to the twelve and says Do you also want to leave? This is a crunch point There is no compromise in this. He offers no further explanation. Jesus is saying I meant what I said. Do you believe in me?
The apostles are confused but Peter answers 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. Jesus has just told them that they must eat his flesh and drink his blood to have eternal life. Now Peter says you have the words of eternal life. So he is accepting that he has to literally eat Jesus flesh and drink his blood to have eternal life because Jesus has said it and Jesus is the Holy One of God, even though he does not understand how this can happen without there being some sort of horrible cannibalistic ritual. And Jesus does not enlighten them.
At the Last Supper Jesus blesses the bread and wine. Does he say Hey guys, remember that time a few weeks ago when I really got you wound up about eating my flesh and drinking my blood? You really fell for it. Of course I was just winding you up. You only have to eat this bread and drink this wine as a sort of symbolic action. We just pretend its my body and blood."
No he says
This IS my body
This IS my Blood
Take and EAT
DRINK from this all of you.
Jesus said what he meant, and he meant what he said.