First I think it is important to understand man's place in all of creation. Did God create man for man's sake, or for His own Glory (Rom 11:36, 1 Cor. 10:31)? If he did create man for His glory, does it matter how and for what He created man? Is He in anyway obliged to man? Another thing if He created man for His own glory, then is it wrong of Him to allow some to be condemned and others be shown mercy Rom. 9:21? Without sin, God's forgiveness and mercy are but two attributes which would never have been revealed. His love (sending His own Son) transcends the attribute of Love that we would have been enabled to understand about Him. Also, remember it isn't God who made man a sinner. Man was made upright. But, because of who God is as the creator, He knew what man would do after creation. The fall was predestined because God knew exactly what man would do in the circumstances of the Garden. God did not make man a sinner, but He did know what would make him a sinner. I like to think (speculation) that because God made man so well, man couldn't have sinned until he was exposed to the tempter. All those born after Adam are born in sin Ps. 51:5. They are not created after the image of God anymore but after the image of Adam. Gen. 5:3. God could have just as well turned His back on the remaining seed of Adam, but instead decided to show His mercy and forgiveness. It is only because of His mercy and grace that any of us are able to rejoice as Children of God, instead of remaining Adam's children, lost sinners whose father is the devil Jn. 8:44. We who are saved now have on Christ's righteousness. This is a quick response, but may be of some help in your thought process.


Hisalone
Matt. 6:33 But seek ye first the kingdom of God, and his righteousness; and all these things shall be added unto you. KJV