That is an excellent question. Jesus is the only way anyone who has ever lived can be saved. His redeeming blood atones for the sins of those living in the Christian era, but also those sins that were committed by those living in Old Testament times too (Hebrews 9:11-15). Therefore, it has been said that the blood shed at Calvary where Jesus died flowed backwards to the sins of Adam and Eve and forwards to the sins we commit today. God has always saved people by His grace through obedient faith (Ephesians 2:8; Hebrews 5:8-9). Abraham was saved from his sins/justified by God's grace (Romans 4:3-4) and his faithful obedience to God (James 2:20-24; Hebrews 11:8-19). To be saved is the same as being considered righteous. To be considered righteous is for God to look at a person as if he or she is just. It is to look at the person just as if they have never sinned, justified.
To be saved today, one must accept God grace, His Son Jesus Christ (John 3:16), and by faith in Jesus Christ (Hebrews 11:6), repent or turn from one's sins (Luke 13:3), confess Christ (Romans 10:9-10), and then be baptized (immersed in water) into Christ for the forgiveness of one's sins (Acts 2:38; Acts 22:16). The person is now a new creation in Christ (Romans 6:3-4; 2 Corinthians 5:17). When one is baptized, the Lord adds this person to the church (Acts 2:47).
I hope this helps. God bless!