I can't say for sure, but I believe in a just God; so whatever the answer to your question is, it will in no way excuse people like you and me who have heard the Truth.
Jesus is in the Old Testament too, as in Isaiah. In that time people, Jews too, had to believe in the promise of the Messiah.
“Before Christ” people were told to look forward to the coming Savior (told to Adam and Eve in the Garden of Eden). “After Christ” people were told to look back to the time in which the Savior did come and paid the price for sin.
So, whether before or after, all were “looking to the savior”. And as the Apostle Paul said of Abraham, he believed the promises of God (in regards to the coming salvation promised and the coming one) and that (just as with us) is counted unto “righteousness” (i.e., “salvation) for him (and us).