There was a deficiency in the ritual of the ceremonial law which should not have surprised anyone who understood it properly. As has been stated (Hebrews 9:25), the high priest was required to go into the holy of holies every year on the Day of Atonement and perform exactly the same ritual all over again, just as he had done the previous year.
How much did the Old Testament people understand? That depended on whether they were true believers or not. The earnest, pious Israelites understood that their worship was symbolic, that it was prophecy, that one day Messiah would come, and though for many years they could not understand exactly how it would happen they were sure he would accomplish the removal of guilt and sin. But of course, sadly, many in Old Testament times did not understand. It suited them to think that their symbolic sacrifices actually accomplished the removal of sin, because that enabled them to sin freely and to be insincere with God, since any time they sinned, they just offered a sacrifice and it was all over. So they chose to think that these animal sacrifices were effective, and gradually, by the time of Christ, the majority of Jews had almost entirely lost sight of the fact that all the ceremonial sacrifices and elements of worship were only symbols.