What was the purpose of the Old Covenant

[Universalist Catholic]

According to the New Testament, the Old Covenant is based on fear, ordinances, laws and flesh.  And we are also told that most Churches mix old and new creating death churches. 

[Song]

I think the purpose of the Old Covenant was to eventually lead to the New Covenant. Maybe God knew that if He showed the New Covenant right away, that people would not understand. I think God had the Old Covenant to show the curse of sin and how we are all guilty under the law. That way, we would be able to understand how liberating and freeing the New Covenant really is.
Romans 3:23 for all have sinned

Here's a UR article I found that mentions this new covenant
https://overcomers.ca/A_Letter_To_The_Body_Of_Christ.html

According to Ezekiel 16:55 Sodom and Gomorrah will be restored to their former estate! Why? So they can commit abominations again? NO! So they can serve God in the NEW COVENANT! Oh I tell you, there is NOT ONE SOUL, NOT ONE, that will not eventually come to enjoy the fullness of Christ's full and complete salvation!

Jesus is Our Savior = New Covenant
Savior from what? Savior from Sin.
All have sin = Old Covenant