Very good post, in fact, excellent thinking! When I translate from the Greek manuscripts, naturally I choose English words that best express the meaning of the Greek word - sometimes one English words will not express the true meaning of the Greek, thusly more than one English term needs to be used. You will see that in many places in most translations, even interlinear versions. I guess you could say if I was to publish what I have translated that I would probably do something in between.
But “is” is the English word the translator chose to use in place of another, another that might just as well, or even more accurately, reflect what Jesus’ words meant since it's possible/likely he was not speaking koine’ Greek here.
Yes, it is possible that Jesus may have spoke in the Aramaic or Hebrew, or even in some dialect of them. However, we do not have any record of what words in what language He spoke; we only have the Greek, so the Greek is what we have to translate. Even the Greek recorded some words that Jesus spoke in Aramaic - very little, but a few - example, while on the cross.
Were they going to eat human flesh or bread? From the wording of the verse alone it can't be answered.
It's too bad most people don't understand that! It's the context that definitely has to be considered to get an idea of what he meant by those words. Also, one has to consider the context of passages wherein others talk about it in the Scriptures. Too many think "literally", while Jesus seems to be using it metaphorically or spiritually; for He did say that "the words which I have spoken to you is/are spirit and is/are life": immediately before these words, he spoke other words that have to be considered seriously - "The spirit gives life; the flesh profits nothing" (my translation of the Greek). These statements of Jesus are an important part of the context wherein He spoke of His body being bread and the fruit of the vine being His blood.
What's your take on John 6 about this?
What do subsequent events show? Well, Jesus had no blood drained from him for his disciples to drink, a violation of the Mosaic Law that Jesus and they were under at the time.
And no flesh removed from his body. (Yes, I know, but you asked my take).
Every language has all sorts of ways of expressing ideas just as in English. The bread and wine represented Jesus’ flesh and blood, no cannibals and vampires amongst the disciples.