Perhaps Jesus can be of service here. With this verse he silenced (Mt.21:16) those leading opponents who stood against him and against the God of Israel. He came to Jerusalem, in a formal sense, to declare his rights to the monarchical headship; which his enemies refused to recognize or give to him. But the praises of even the youngest enthusiastic celebrant (v9) put those indignant mules to shame.
The worshipful voices of little children singing this Psalm, or any other, is a potent witness against the most powerful of the Lord's enemies. The speaker, David, king David, belittles himself further on in the Psalm, asking how it is reasonable that the God of the universe should even notice a man, yea the Representative man himself and head of the congregation. "Who am I to praise you, and have you receive that praise as something other than contemptible?"
Still, the Creator has lifted man to a position of dominance over all the works of his hands in the world. And it is beyond fitting for such to praise him; therefore we will, from the least (the smallest, youngest, weakest) to the greatest.
My daughter asked one of the children that she baby sits for, "What did you learn about in Sunday School today?" This three year old smiled and without hesitation responded, "Jesus." If only we adults could always respond this way. The eternal Logos has perfected praise in these little ones.