In other cases, when Jesus told a parable, and the crowd didn't understand, He explained, rephrased, told it another way. In John 6, the crowd murmured and didn't understand, and He said it again -- the same way. And a third time. And then many of them left.
You have to see what's actually before you. You know the maxim: you only resort to interpretation and construction when the language is not plain. And Jesus's words are just about as plain as it gets.
“You know the maxim: you only resort to interpretation and construction when the language is not plain. And Jesus’s words are just about as plain as it gets.”
That is as superfical as you can get. Do you actually know much about allegorical language, and John’s abundant use of it, and what He means by believing elsewhere, and how one gets life?
Consistent with your interpretation of Jn. 6, then then no one has life in them (being born again: Eph. 2:1) until they literally eat his flesh, (Jn. 6:53) and Jesus lived by eating His Father’s flesh, as believers do who eat His, (Jn. 6:57) and the “word of eternal life” (v. 68) is not believing the words of the gospel, which elsewhere is what the Bible gives eternal life, (Jn. 3:13,16,36; Acts 2:38; 10:43; 13:39, etc.) but refers to physically consuming Jesus!
And consistent with your rejection of John’s use of allegory, Jesus was an actual door, (Jn. 10:9) an actual lamb, (Jn. 1:29) an actual vine, (Jn. 15:1) and eating meat was how He did the Father’s will. (Jn. 4:34) In addition, Jeremiah really did eat God;s words, though we do not know which Bible version he used, and David turned water into blood. (2Sam. 23:17)
Your exegesis is manifestly erroneous, though all this chapter has not been infallibly defined, so you have some degree of freedom, while you should not even be trying to use the Bible to convince us, as it is only by the infallible magisterium that we can know such for sure. And which relies upon itself for its authority.