That is an amazing question. God is all in all and is singularly with asiety. It is to ask does the creator of all things have a purpose? A more appropriate question would be, whats the purpose in all His creations. All that He has created serves His purposes and they display the magnificence of these innumerable creations in every form of life.
Man was created in the image of God, which is to say we share some of His attributes, love, anger, jealousy, kindness, forgiveness, vengefulness, compassion, just to mention a few.
The closest I can come to answering this question, is that the purpose of creation, is to serve Gods pleasure and to reveal to us that part of Him we can most relate to, life.