Why is the Old Testament law seen as deficient?

Hebrews 10:1 describes the law as having a shadow of good things to come but not the reality itself, meaning it was insufficient for achieving true righteousness. The offerings and sacrifices made under the law served as reminders of sin rather than providing redemption. They were never able to cleanse the conscience of the worshippers completely. The law highlighted sin and the need for a better sacrifice, ultimately pointing toward Christ, who fulfilled the law and provided true salvation through His own sacrifice.