The Jews were asking Jesus for a sign like manna from heaven. When Jesus began talking about Himself being the bread of life that gives life to the world & how to receive that bread of life by coming to & believing in Him, the Jews were still stuck in that mentality of seeing that sign of manna from heaven to eat.
John 6:30 They said therefore unto him, What sign shewest thou then, that we may see, and believe thee? what dost thou work?
31 Our fathers did eat manna in the desert; as it is written, He gave them bread from heaven to eat.
32 Then Jesus said unto them, Verily, verily, I say unto you, Moses gave you not that bread from heaven; but my Father giveth you the true bread from heaven.
33 For the bread of God is he which cometh down from heaven, and giveth life unto the world.
34 Then said they unto him, Lord, evermore give us this bread.
35 And Jesus said unto them, I am the bread of life: he that cometh to me shall never hunger; and he that believeth on me shall never thirst.
36 But I said unto you, That ye also have seen me, and believe not.
37 All that the Father giveth me shall come to me; and him that cometh to me I will in no wise cast out.
38 For I came down from heaven, not to do mine own will, but the will of him that sent me.
39 And this is the Father's will which hath sent me, that of all which he hath given me I should lose nothing, but should raise it up again at the last day.
40 And this is the will of him that sent me, that every one which seeth the Son, and believeth on him, may have everlasting life: and I will raise him up at the last day.
41 The Jews then murmured at him, because he said, I am the bread which came down from heaven.
Because they were still stuck in that mentality of eating manna from heaven as a sign in order to believe in Him when He is right there for them to believe in Him to be saved. And He said this to be clear to His disciples plainly enough that He was not only referring to His crucifixion but His ascension as well for why we are believing in Him.
John 6:61 When Jesus knew in himself that his disciples murmured at it, he said unto them, Doth this offend you?
62 What and if ye shall see the Son of man ascend up where he was before?
63 It is the spirit that quickeneth; the flesh profiteth nothing: the words that I speak unto you, they are spirit, and they are life.
64 But there are some of you that believe not. For Jesus knew from the beginning who they were that believed not, and who should betray him.
65 And he said, Therefore said I unto you, that no man can come unto me, except it were given unto him of my Father.
66 From that time many of his disciples went back, and walked no more with him.
He told them to listen to His words about how believing in Him is how they receive the bread of life, hence eternal life as He expounded from His crucifixion to His ascension to His disciples for why we are believing in Him to be saved.
He had told Nicodemus the same earlier about when one is born again which is after His ascension, which is after His crucifixion for whenever any one believes in him to be saved as drawn by the Father to believe in His Son.
John 3:13 And no man hath ascended up to heaven, but he that came down from heaven, even the Son of man which is in heaven.
14 And as Moses lifted up the serpent in the wilderness, even so must the Son of man be lifted up:
15 That whosoever believeth in him should not perish, but have eternal life.
16 For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life.
You just cited Jesus saying that previously.
John 6:63 It is the spirit that quickeneth; the flesh profiteth nothing: the words that I speak unto you, they are spirit, and they are life.
He said it earlier again prior to that.
John 6:48 I am that bread of life.
49 Your fathers did eat manna in the wilderness, and are dead.
50 This is the bread which cometh down from heaven, that a man may eat thereof, and not die.
51 I am the living bread which came down from heaven: if any man eat of this bread, he shall live for ever: and the bread that I will give is my flesh, which I will give for the life of the world.
52 The Jews therefore strove among themselves, saying, How can this man give us his flesh to eat?
He had told them how to receive the bread of life by believing in Him but because they were stuck in not believing in Him and His words, He went to the metaphor of His crucifixion.
I believe the Word of God as in Jesus Christ is the Creator. The apostle John said so.
John 1:1In the beginning was the Word, and the Word was with God, and the Word was God.
2 The same was in the beginning with God.
3 All things were made by him; and without him was not any thing made that was made.
4 In him was life; and the life was the light of men.
10 He was in the world, and the world was made by him, and the world knew him not.
11 He came unto his own, and his own received him not.
12 But as many as received him, to them gave he power to become the sons of God, even to them that believe on his name:
13 Which were born, not of blood, nor of the will of the flesh, nor of the will of man, but of God.
14 And the Word was made flesh, and dwelt among us, (and we beheld his glory, the glory as of the only begotten of the Father,) full of grace and truth.
I believe the Word of God had asked the Father for Them to make man in "our" image and after "our" likeness, and so when the Father agreed with the Holy Spirit in compliance, the Word of God created man in His image and after His likeness. That is why when our Creator was crucified on the cross in taking our sins upon Himself, this act was seen in creation as the light of the sun and the full moon was blacked out and Jesus as God, experienced the separation from the Father. That is the awful experience the Son of God as God had experienced in taking our sins unto Himself in giving His life as a ransom for many. Fortunately for us, He has risen from the dead & ascended to Heaven leading the way for us in bring us to God the Father as Jesus is the God Our Redeemer and not just as the God Our Creator.
This prophesy below of the Lord God Our Redeemer speaking is about His water baptism by John the Baptist for when the Father bore witness from Heaven along with the witness of the Holy Ghost as sending God Our Redeemer.
Isaiah 48:16 Come ye near unto me, hear ye this; I have not spoken in secret from the beginning;
from the time that it was, there am I: and now the Lord God, and his Spirit, hath sent me.
17 Thus saith the Lord, thy Redeemer, the Holy One of Israel; I am the Lord thy God which teacheth thee to profit, which leadeth thee by the way that thou shouldest go.
Matthew 3:15 And Jesus answering said unto him, Suffer it to be so now: for thus
it becometh us to fulfil all righteousness. Then he suffered him.
16 And Jesus, when he was baptized, went up straightway out of the water: and,
lo, the heavens were opened unto him, and he saw the Spirit of God descending like a dove, and lighting upon him:
17 And lo a voice from heaven, saying, This is my beloved Son, in whom I am well pleased
May God cause the increase to enable you to see the Truth in His words as Jesus is the God men had seen in the O.T. that Moses had written about in scriptures.
John 5:39 Search the scriptures; for in them ye think ye have eternal life:
and they are they which testify of me.
40 And ye will not come to me, that ye might have life.....
46 For had ye believed Moses, ye would have believed me; for he wrote of me.
47 But if ye believe not his writings, how shall ye believe my words?
