Question:  Also, were those not Jewish before Christ saved through the same way, a realization of their spiritual depravity and of their need to be saved from that?

Yes!  In Romans 4:9, Paul, speaking about Abraham says, “We say that faith was counted to Abraham as righteousness.”  Abraham came to God by faith just like any believer today comes to God.  Paul reasserts in Ephesians 2:8, “For by grace you have been saved through faith. And this is not your own doing; it is the gift of God.”  Hebrews 11:6 echoes this same message, “And without faith it is impossible to please him, for whoever would draw near to God must believe that he exists and that he rewards those who seek him.”