When we sin, a blood sacrifice is required (Hebrews 9:22). For this reason, Jewish people/Israelites would take animals to the priests, and the priests would kill the animals and use the blood to atone for the sins of the people. This system is described in Leviticus. The system did work temporarily, but the Jewish people had to continue these sacrifices year after year (Hebrews 10: 1-4).
Lambs were often used as blood sacrifices. It was no coincidence that John the Baptist said these words when Jesus approached him: “…Behold the Lamb of God, which taketh away the sin of the world” (John 1:29 KJV). This is because Jesus came to replace the sacrifices that the Jewish people made continually.
Hebrews 10:10 settles the matter: “ But this man, after He had offered one sacrifice for sins for ever, sat down on the right hand of God” (KJV). Jesus’ death did the job for us once and for all AND for everyone, Jewish people and Gentiles alike.