Q: Why did GOD create the universe, intelligent creatures, animals and other non-living things? What was his main purpose on this big project?
A: Thanks for your note to us here at TruthBook.
For this thoughtful question, there is this beautiful answer, from The Urantia Book:
32:5.7 There is in the mind of God a plan which embraces every creature of all his vast domains, and this plan is an eternal purpose of boundless opportunity, unlimited progress, and endless life. And the infinite treasures of such a matchless career are yours for the striving!
The goal of eternity is ahead! The adventure of divinity attainment lies before you! The race for perfection is on! whosoever will may enter, and certain victory will crown the efforts of every human being who will run the race of faith and trust, depending every step of the way on the leading of the indwelling Adjuster and on the guidance of that good spirit of the Universe Son, which so freely has been poured out upon all flesh.
For me, this says it all. God's plan is unfolding day by day, and it is a plan born of God's amazing LOVE, and to satisfy his eternal purposes. I hope it satisfies your question. Please see The Eternal and Divine Purpose to read this complete section.
Our God is an awesome God!