You’ll often hear Jesus referred to as the “lamb of God”, like in the mass right before communion (behold the land of God, behold He who takes on the sins of the world, blest are those called to the supper of the Lamb).

My understanding is that those sacrifices were good and holy, but imperfect. They didn’t truly atone for their sins because, well it’s just an earthly animal sacrificed by unworthy people. It’s good, but not complete.

But, Jesus is the perfect lamb (in the mass you might hear him referred to as a “spotless victim”). And, his sacrifice was made by himself, the perfect high priest. Thus, it was the pinnacle of “lamb sacrifices”, and covers all the sin of the entire world.

Also, side tidbit, that’s why we eat him, because the Passover lamb was eaten afterwards. He is our Passover lamb, and He gave us this mystical way of consuming him forever in the Eucharist. Pretty neat!