Yes, a person. Jesus' blood is part of his personage. There is no conflict there. The scripture citation above just narrows down exactly what about that person is the object of faith for a Christian. You can't say you accept Jesus but not his blood covenant and expect your condition to change. This is where the WT goes too far South and promotes self-liberation by their "growing to perfection" doctrine.
About Human Sacrifice:
Every man and woman who has ever lived has been a victim of human sacrice. Man is incapable of self-liberation by any means. "The wages of sin is death, but the gift God gives is everlasting life by Christ Jesus our Lord". (NWT) Christ's blood pays this debt vicariously, if we accept it.
God puts an end to Human Sacrifice. We were created for His enjoyment, his pleasure, his family, his love and his Life to be within us, as it is within him.