Why God does what he does?

And God said, Let there be light: and there was light -Genesis 1:3 KJV The almighty God gets what he desires and what he wants is good indeed. I believe there's a ultimate goal for humanity (as a whole) to achieve and humanity will reach that point eventually. It's just the road and (not the destination) that bothers me. The unbearable amount of suffering and grief that one experiences during his life **is not fair**, for example; when Gaza war started I saw a video clip of a dad taking his little daughter's severed body parts which was in a plastic bag to a ruined hospital, desperate, maybe he was hoping he can get his daughter back? Humanity doesn't have a clue what he's doing, no one is born with a PhD, we all do terrible terrible mistakes and not many have the chance to learn why they should turn the other cheek. So this thoughts always left me with this question; - Was it necessary to let humans go down this path? What important part are we going to play in this "scenario" of God's creation that made our poor souls worthy of suffering? And no we did not choose the path of destruction and death, we went that way because we did not knew the ultimate consequences of our actions, If Adam TRULY knew that he's going to cast out of heaven or what not being in heaven is like, would he still have done it? David, the God chosen prophet committed adultery, he had **everything** and yet the lust got him. How can one resist sin when David couldn't?