God didn't create sin. Sin is anything opposed to God's nature. It isn't God's will that we sin, it's God's will that his creation has a choice and the ability to sin is an unfortunate side effect of that. He could've made us without the ability to choose sin, but without choice there can be no love. And yes sacrifices are horrendous. That's the point, it served as a reminder of the penalty of sin, which is death. And ultimately, he came to earth, lived a sin free life and made the final sacrifice for our sins.