Not exactly sure why we are disagreeing? But, the Jews did say to Jesus that they had manna in the wilderness, and asked what sign He would give them.
When you stated
Well this is our work, yes! Believe! Jesus replied to the one who asked about this very thing.
Joh 6:28 Then said they unto him, What shall we do, that we might work the works of God?
Joh 6:29 Jesus answered and said unto them, This is the work of God, that ye believe on him whom he hath sent.
So many people use this out of its context. They read Paul's mystery grace revelation into it when that was not the intention of what Jesus was saying above.
John wrote his gospel as a record of the 8 signs that Jesus performed in order for Jews to believe that he is their promised Messiah (John 20:30-31).
In that record,
the signs are seen as works of God. There are at least two times the John account explains that.
John 10:
24 Then came the Jews round about him, and said unto him, How long dost thou make us to doubt? If thou be the Christ, tell us plainly. 25 Jesus answered them,
I told you, and ye believed not: the works that I do in my Father's name, they bear witness of me.
John 14
10 Believest thou not that I am in the Father, and the Father in me? the words that I speak unto you I speak not of myself: but the Father that dwelleth in me, he doeth the works.
11 Believe me that I am in the Father, and the Father in me: or else believe me for the very works' sake. 12 Verily, verily, I say unto you, He that believeth on me, the works that I do shall he do also; and greater works than these shall he do; because I go unto my Father.
Once you understand what John was trying to do in his gospel, this verse you quoted is not saying we are trying to make it say, after we read Paul's revelation of the mystery.
Jesus was not saying to "believe in his death burial and resurrection and that is all you need to do to be saved." He was telling the Jews to believe in the signs, that he is their promised Messiah.