Greetings again pilgrim. If you are an evolutionist, don't write off this stuff immediately. What is written here is working with the premise that God created the world and does not presume at this point to state how he did it. I will look at this another day. So, why did God create this world; this universe? And why did he create us?
The first reason is that he created to express his character. As a creative being, creating is something which flows from God in the same way as painting flows from an artist or a song flows from a composer. God is the ultimate artist, scientist, architect and builder. As such creation is inevitable where God is concerned. This makes it probable to me that there is more to God’s creation than that which we can observe and experience. Concepts like other planets with life, aliens, the multiverse and other unimaginable creations are natural to my view of God. There is nothing in the bible to rule out such an idea despite what some Christians claim. Were we to discover intelligent life forms on other planets or dimensions, for me, this would cohere with the biblical concept of God.
Secondy, he decided to create a world for his created people. The whole point of the creation of the world was to create an ideal environment for humanity to exist in. The picture of the garden of Eden and the wonderful flora and fauna of the earth is for humanity to live in a wonderful free loving relationship with God, free of suffering and evil (read Genesis 2).
Thirdly, he created to create free volitional free creatures with whom he could live in eternal volitional relationship. Put another way, the whole point of creation is love. God is love, meaning that he is relational, wanting to love and to be loved. We humans are created to live with God forever and ever in a relationship of love. He wanted us to do this by choice not by coercion i.e. he wants to spend eternity with those who want to be with him.
Fourthly, he created because it was worth the risk. God knew at the point of creation that it was possible that he would be rejected and evil would rule. In fact, in terms of his omniscience (all-knowledge), he knew that humanity would rebel against him. However he still wanted to create knowing that some would accept him and live eternally with him in a relationship of love.
So he created you to be his companion and friend, to exist with him forever and ever. He wants to bless you and he wants to know you. Will you let him?