Why did God require animal sacrifices in the Old Testament?

yes, the life is in the blood..the animals were innocent, with their not knowing right from wrong no guilt could be laid upon them..the shedding of blood made amends for mans inability to follow the law and sin..the law was given by moses, and was for gods chosen people...however god was disappointed with their inability to follow the law and their turning their backs on god so he sent his son who lived the law without any mistakes which fulfilled the law and died innocent on behalf of all mankind..now regardless of race ALL men woman and children have the opportunity to call on jesus and be saved