The psalmist is in a reflective mood. He starts and finishes with the same observation. He has looked up at immensity of space; looked at the beauty and variety of creation surrounding him and finally looked at himself. He is amazed at his own vulnerability and transient life in comparison to the permanence of everything within his reach. Nevertheless, he is the crowning glory of all the Creator has made.
The truth dawns on him that is he was not made a little higher than the ape but just a little lower than the angelic beings. That makes him unique. Originally made in his image of righteousness and holiness we became flawed through sin. But we can be restored to a right relationship with God in Christ. It is called the gospel.