I'm wondering if, at the Last Supper, when Jesus said "take and eat, this is my body; take and drink, this is my blood," was that an idea his disciples would have somehow recognized from another tradition? Was it something completely new and revolutionary for a Jewish person in that geographic region to say? Is there somewhere that Jesus (or the authors of the gospels) might have gotten the idea from?
This answer from 4 years ago might interest you: https://www.reddit.com/r/AskHistorians/comments/7hg14g/symbolic_cannibalismwhat_was_the_thinking_behind/
I'd argue this is built primarily around the Old Testament concept of the sacrificial lamb. At the time right before Exodus called the Passover, the family had to sacrifice the lamb, spread is blood on the door, and the lamb had to be consumed by the family and whatever other people were with them in the house.
As a parallel, John calls Jesus the Lamb of God. Jesus Himself is placed on the cross (his blood spread in a way on the wood), and He is consumed by Catholics in the Eucharist/Communion. In this way we are joined as close to God as possible on Earth, which is why the Catechism says the Eucharist is the source and summit our faith. It's no mistake that Jesus has the Last Supper on Passover.
This was an idea rejected by some even in the Bible, as can be seen in John 6:66.