Our purpose is to bring glory to God. God didn't have to create us but created us for his enjoyment. We can glorify God through whatever we do. Our whole lives we should bring glory to God.
Answer 2To serve God. This is a good answer, however it is unprovable. Man has several purposes on this earth which are observable. One, is that he populates the earth. Two, being the higher form of life--meaning endowed with intelligence--he has to take care of this earth. Three, being an animal he is part of the food chain. He is a predator, or in the case of parasites he is the prey. Ultimately, when man dies he is food for bacteria.
Answer 3From a Latter-day Saint Christian [Mormon] viewpoint:
God organized this earth so that He could bring about the immortality and eternal life of His (already existent) spirit children. We could not be proved nor could we be saved in heaven while while living with God. We had to prove ourselves as independents to be worthy of reward and glory. Also, as mere spirits only, we could see that God, Our Father, had an Immortal, Glorified Body of flesh and bone. And we wanted to be like our Father. Without such a body, we cannot experience a "Fullness of Joy": spirits only are extremely limited in the measure of Joy they can attain to.
So God created a physical earth whereon we could receive bodies and learn to control and grow our bodies, and learn to choose the right when not in His presence - to prove ourselves, you might say.
If we prove worthy over this [granted] lifetime ... if we repent and learn to grow and "overcome" - both physically and spiritually, we will prove ourselves worthy to return into His presence Forever - not just as spirits, but as complete Beings, progressed - worthy to receive Immortal glorified bodies - as Jesus: "Joint heirs with Christ in all that the Father hath" (as promised in the Book of Romans). As we call upon God to forgive us and put into effect, in our lives, the death, atonement and resurrection of Jesus Christ, being literal spirit children of God, we can become like Him, as we also become clean before God.
The Creation and placement of the earth forms a major part of this whole process for us to progress and become like our dear Father in Heaven.
In esence, man is here to progress to become more like God in character - to develop faith when away from His presence, to learn to keep the commandments and to gain physical bodies.
Be a Man was created in 2000.
Plastic Man was created in 1941.
Man the Hunter was created in 1968.
The Outside Man was created in 1973.
I Killed That Man was created in 1941.
What a Man My Man Is was created in 1974-10.
The Man Who Was Almost a Man was created in 1961.
What a Man My Man Is - album - was created in 1974.
Man Is Wolf to Man was created in 1998.
No-Man was created in 1986.
A Man was created in 1979.
Be a Man was created in 2000.
If I Was a Man was created in 2008.
If I Was Your Man was created in 2006.
If This Is a Man was created in 1957.
Man of Me was created in 2001.
Where Is My Man was created in 1983.