Our God is absolutely holy. That means that He's totally separate from and far above all His creation. He doesn't need anything to make Him happy, for He is and should be entirely satisfied with His infinitely glorious Self. All creation gloriously expresses His Nature, yet it mustn't be assumed that He has any need for that expression. He is not incomplete without it. God creates because it's His nature thus to express Himself, not out of any need for it.
That's the theme of David's hymn of praise and wonder here in Psalm 8. When he leads the worshippers to sing, "O Lord our Lord, how excellent is Your Name in all the earth, Who have set Your glory above the heavens," he's praising the Self-existent, Self-sufficient, yet at the same time Self-expressing God.
Yet while he praises the God Who is high above even all these Self-expressing works, yet he is also praising the God Who allows even the humblest of His creation to bring Him praise: "Out of the mouth of babes and nursing infants You have ordained strength."
David is referring to himself. Though he isn't literally a "babe" or a "nursing infant," yet in comparison both to God Himself and to the majesty of the creation, he is as comparatively helpless as they. And by inspiring and allowing even such an insignificant one as David to be the successful king of God's people, God thereby reveals His own keeping, strengthening, blessing power - and therefore silences Israel's enemies.
But the thought of such an infinitely wise and powerful God awes David. He's forced to say, "When I consider Your heavens, the work of Your fingers, the moon and the stars, which You have ordained, what is man that You are mindful of him, and the son of man that You visit him?" He's amazed that so great a God would use humble mankind (including himself) to accomplish His works!
For this reason he goes on to express the amazing privilege and responsibility God has bestowed upon mankind - to be over "the works of Your hands." By using such humble servants, God just reveals His own immense wisdom and power in the earth, and David therefore concludes by singing, with all his might, "O Lord, our Lord, how excellent is Your Name in all the earth!"
We should join David in this song of praise. It should be our song as well as his. Let's thank our gracious God for giving us work to do in this His world, however humble or seemingly insignificant. We do it by His wisdom and power, and we thereby reveal His glory in what we do.