We are talking scripture not theology.
How can you tell?
Read the Old Testament! I am sure you don't believe that has changed too. Find in it one instance where Satan (ha-satan) is linked to, associated with, or called "the devil."
Satan is mentioned only a few times in the OT. In none of those instances is he portrayed as anything but God's loyal servant, and not a rebellious, fallen angel.
The word "devil" who is synonymous with Satan appears for the first time in Deuterocanonical books and from there in the New Testament. The fall of Satan is mentioned by +Luke, +Paul and +John. Whine this cannot be found in the mainstream Jewish canon, it is in deterocanonical books. My point was and is: the so-called "apocryphal" books were included in the Christian canon because the Apostles used them extensively, while the Protestants reject them. That makes the disconnect glaringly obvious!
What you're asking me to do is to make suppositions based upon a few verses. Since Satan is rarely mentioned in the Old Testament, therefore the ancient Jews believed "X" about Satan. That's rather difficult to do. I can only go by what's recorded and I don't have access to records.
I will caveat all this in saying that, assuming you were correct and our Jewish forefathers believed this about Satan, what would it matter? It doesn't affect the inspired writings which are record through men by God. Christians can get a more complete picture of Satan through the New Testament which unbelieving Jews reject. The picture we have is based upon what believing Jews recorded.
Doctrine evolves as our understanding does. As an Orthodox you most certainly should understand this. Jewish doctrine is totally wrong as far as a Christian believes. Anything our Jewish friends believe about Satan not based upon the completed text is, to a Christian, incomplete at best.