Exactly! The Protestant God designed and made the Creation, created man in a pristine world, then "planted" a serpent to tempt him -- knowing exactly that man will fail because God desired it so! This brings terrible demise of mankind, and then God decids to kill Himself on the Cross so as to redeem us when all this is not our doing but His!
Could it be that God decides also what He wnats to know and what He doesn't want to know? Can He will not to know? I don't know! But what I do know is that if He predetined everything, the whole idea of sending His only begotten Son to suffer and die for the redeption of sin that He caused, planned, authored and executed, is somewhat dubious as you hint.
It appears to me that you do not believe that God is either omnipotent or omniscient.
In other words, it appears that you are saying that God is helpless in the face of evil and that God does not know the future and that he created the world with absolutely no idea as to how it would turn out.
Who do you think "planted" the serpent? Johnny Appleseed?
...knowing exactly that man will fail
Do you think God did not know Adam and Eve would succumb to the serpent? Thus the fall of the entire human race was a surprise to God?
"Oops," says God, sovereign Creator of heaven and earth. "I sure didn't see that one coming."