If God created everything why didn't he create it perfect?

If you went and made a scale train on an 4x8 you would expect/want all to move and stay on the track; but on occasion the train will jump the track. If it did stay just right on the track wouldn't you get board? God gave us the ability to decide on our own. When people run from God, to be so selfish, they disappoint God and often end up hurting others.