Hebrews 9:26 He then would have had to suffer often since the foundation of the world; but now, once at the end of the ages, He has appeared to put away sin by the sacrifice of Himself.
The high priests had to offer themselves as well as their sacrifices often to appease God. The sacrifice was an offering for the sin and if that was not sufficient then their lives were on the line as they entered the Most Holy place.
Jesus Christ came and offered up a perfect sacrifice which was sufficient for all sin for all mankind.
That is how much God loves us and continues to love us; that single sacrifice was enough for all sin!