He also said “The Spirit gives life; the flesh counts for nothing. The words I have spoken to you - they are full of Spirit and life.”
You are assuming, incorrectly, that it must be either/or. It is the Spirit that gives life through the Body and Blood of Jesus. Thus, as you quoted above, Jesus says: "The words I have spoken
Amen, amen, I say to you, unless you eat the flesh of the Son of Man and drink his blood, you do not have life within you. Whoever eats my flesh and drinks my blood has eternal life, and I will raise him on the last day. For my flesh is true food, and my blood is true drink. Whoever eats my flesh and drinks my blood remains in me and I in him.are spirit and life.
To refuse to accept the reality of Real Presence one must isolate the verse you quoted from the rest of Scripture and the practice of the early Church (including Paul) from whom we get the Scriptures.