You have made a very important observation--one however that many people never make. Our salvation today has a completeness at the moment of salvation that was not known before the death, burial, and resurrection of Christ. Of the Old Testament saints, Hebrews 11:13 states, "These all died in faith, not having received the promises, but having seen them afar off." They died in faith, but they had not received the promises. When compared to our salvation, you could almost say that these saints were secured and not saved--at least not in a completed sense. By secured, I mean that they were preserved until the blood of Christ could be applied to their souls. Hebrews 9:15 teaches, "And for this cause he is the mediator of the new testament, that by means of death, for the redemption of the transgressions that were under the first testament, they which are called might receive the promise of eternal inheritance." Notice that the death of Christ (as the mediator of the new testament) was necessary for the redemption of the transgressions that were under the first testament (the shedding of the blood of animals in sacrifice). That is, their souls were not saved by the sacrifice of animals. They had to be preserved until the shed blood of Christ was applied to them. This probably explains why Abraham's bosom is located adjacent to hell before the death of Christ (Luke 16:22-26). The Old Testament saints are probably also those referred to in Ephesians 4:6, "When he ascended up on high, he led captivity captive, and gave gifts unto men." After the death and resurrection of Christ, the souls of these saints could be taken into heaven with no problem.
How can anyone be saved before the saving work of our LORD JESUS CHRIST? If even one person could be saved without his blood, then does that mean that the FATHER is evil, putting his son to useless suffering, for if HE can save one can HE not save them all the same way? The Bible says that if righteousness could be given by the law, then it would have been given, but it is not possible.