John chapter six isn’t about the Lord’s Supper, but it and the Supper are about the same truths. In both, Jesus uses a metaphor to point us to Himself, and one thing He tells us is that He is a meal, not a feast.
These Galileans failed to realize they were coming to the King of kings, not Burger King. You cannot have this bread your way. When Jesus tells them there is a heavenly Bread that endures for eternal life, they ask for it (John 6:34). They want eternal life, but they want only a meal, not a feast. They want Jesus as they want Him (cf. John 6:14–15).
Jesus’ doesn’t make himself palatable to sinful tastes. He pushes the metaphor to the extreme to their disgust. Jesus keeps saying “Mana. Mana. Mana.” Like their forefathers they grumble at the heavenly Bread the Father has provided, proving themselves to be another generation doomed to perish in the wilderness due to unbelief (cf. Hebrews 3, 1 Corinthians 10:1–11).
Jesus then has the audacity to tell them that He isn’t an acquired taste, but a given taste (John 6:37, 44–45, 65). You can’t by effort come to taste and see that Jesus is good. If you savor the Savior it is because your mouth has been washed by the waters of regeneration to give an appetite called faith. Jesus says that eating is coming and drinking is believing. Jesus is the eternally satisfying Bread of life to His people because they never stop eating, meaning, they never stop believing.
Man knows this much, he is hungry and thirsty. The problem isn’t a lack of appetite, but what we try to satiate that appetite with (John 6:27–29). There are many variations of the fountain of youth/life legends. Imagine that such a fountain exists in a narrow cave, but there’s a catch. There’s always a catch huh? Once you drink of the fountain you have eternal life, but you cannot leave the cave. Once you do, you die immediately. Man wants eternal life, but he wants to leave the cave. He wants Jesus as a meal, not a feast. He wants to drink the fountain only to enjoy other drinks. But what if the only thing worth devoting an eternity of existence to was knowing and enjoying the fountain? This is one of the many things we declare and anticipate in the Supper, that day when the bride will forever feast with her Beloved, and her every desire is fully satisfied in Him.