David is the writer of this Psalm. He was acquainted with nature as a herdsman, he viewed the land and plants and animals when he was alone in the fields. He recognized mankind's supremacy under God's authority to use the animals and their contributions to life. He valued them as God intended them for our use.
He also questions the supremacy of man in the creation. What is man that God considers him? Man is the creature that communicates with God with conscience and care. The animals are subject to instincts and are not required to be moral or decent. Man has a responsibility to the rest of his race and the creation in which he is the master. Moreover, he has a responsibility to God for his own behavior. David gives us a model to follow: We are to acknowledge God and obey his commands.
Sounds simple, doesn't it? And yet we see failure on every venue. Look again: We have an opportunity to be what God has called us to be every time. Try it one more time. Be that man or that woman God calls you to be.