Here is my belief which answers your question.
We are just not creations of God but God’s children. Yes every one of us will become Jesus, who will inherent everything in the universe as kings and children of the King. But till then…
We are gods, we have been given great (spiritual) powers, most don’t know our own power, some of us have ceded power to others.
We, running the world as a bunch of gods, and we are still not perfected in our ways (we are not yet Jesus), put anger, hate and other things in the world. Those things cause all pain and suffering in the world.
God (big G), allows us to rule as we do. Eventually, maybe through many lives, we will see the suffering we have caused because we are not yet Jesus, some very far apart from Jesus. We see the karmic cycle that if you put anything into the world (love, hate, whatever) it grows throughout humanity, and if not Love comes back to bite you in the ass when it is fully grown.
Through this we learn that we want to put Love out in the world, that we realize that Jesus’ way was the only way. Though you may not know Jesus by name, all you need is Love, and realize that Love can be born in your heart, they you become a child (son or daughter) of Love - then you are who we call Jesus.
Scriptures state God is one. So Jesus is the Father, is the Spirit is whoever accepts the way of Love. They are all the same, yes people following the path of Love are Jesus, they are as much Jesus as Jesus Himself (this fully includes females and the feminine but don’t want to go into gender issues).
The Holy Spirit can be thought of as the whole(y) Spirit, the one ‘whole’ spirit, the same one that lives in the Father, and Jesus, and the saints, and all with Love in their hearts.
A good way of understanding this wholeness or ‘oneness’ is to see how the mother/infant relationship is to the infant. To the infant the mother is part of the infant. To go further back, and this is my personal revelation but may help with understanding the term ‘oneness’ and ‘God is one’, a child in the womb is one with the mother to a much greater extent. The child senses through the mother, the cravings that a pregnant woman has are the desires of the child. The in the womb child is a very nascent consciousness at this state, but a real living one. This is our relationship to big G God (the Father) we are one with Him, having one spirit with Him.
So to answer your question, there is suffering because we are god (little g, or a fractional disconnected part of God (big G), and that is needed because we will become God (big G). But we must decide that is what we want because we agree with big G God - this is the free will issue.