This was written before Christ was born as a man, it answers the question about whether there was salvation before Christ. Christ fulfilled it and made it perfect. Christ solved the mystery of salvation for man.
We are told it wasn't the blood of animals that worked for salvation those 4,000 years before Christ. Blood was used by pagans to feed gods. The true God hated it when His people copied that. It was the symbol of the blood God gave for the atonement of sins as is told in Lev. 17:11. It was the blood of Christ as it was in eternal time rather than in our kind of time that atoned for sin.
The NT explains the OT, and the OT explains the NT. They are breathed by God and always agree.