Deuteronomy 8:3 And he humbled thee, and suffered thee to hunger, and fed thee with manna, which thou knewest not, neither did thy fathers know; that he might make thee know that man doth not live by bread only, but by every word that proceedeth out of the mouth of the Lord doth man live.
God took them where they would need Him. He allowed them to get hungry. He then fed them with a miraculous food called manna. He did that so that man would understand that he needs the Word of God.
So the story about the manna was to teach us the importance of God’s Word and our spending time in it and learning what God has to say.