Nicodemus observed some signs of who Jesus is, but wants to know what is important.
To enter the Kingdom of God, you have to be born again, or from above. Nicodemus would, as a Pharisee, think that his position in the Kingdom of God was assured - he thought he had done all that was needed to be accepted by God. God, in Ezekiel, promises to clean us, dealing with our moral pollution. The dry bones in Ezekiel's vision had no trace of what the people had been. Ruach, means breath, wind or spirit - used ten times in the passage.
The Israelites bitten by snakes in the wilderness where healed by God's grace by looking at the lifted up bronze snake. Similarly, those who look to the crucified Christ are those who will receive eternal life.