The original belief of the Israelites was the same as that of other Canaanites.
No one knows what our original belief was, and that we were Canaanites is possible, but not a gimme.
As Augustine said, you can call then gods (as often in the psalms) or call them angels: it doesn't really matter.
But "God" or "gods", as used in both the Hebrew and Christian scriptures, never appears to have referred to angels.
As for Yahweh, he was the guardian angel or god of the Israelites: "When the Most High gave the nations their inheritance, when he divided mankind, He fixed the bounds of the peoples according to the number of the children of God ; for the Yahwehs portion is his people, Jacob his own inheritance." (Deut. 32; from the Septuagint, for the Hebrew text is later and has be altered). So Yahweh told Moses "I am your god", not "I am God the Father Almighty", and Moses asked his name. Also Jephthah obviously considered Kemosh as equal to Yahweh. (Judges 11) Eighth-century inscriptions in Israel show that El (God} and Yahweh were still distinguished. The idea that they were the same appears about the same time in Judah but it wasn't fully established until after the Babylonian Captivity (fifth century).
There are roughly 16 different names for God as found in Torah and Tanakh, so one shouldn't at all assume the above. Many of these names come from the Sumerian language, but even though the Sumerians were polytheistic, and it's quite possible our early ancestors may have also been polytheistic. However, they are used exclusively as a monotheistic reference in Torah.
So are Christians and Jews worshiping the same god? Well, since they are both intending to worship the creator, they both intend to. As Augustine and Aquinas pointed out, if you acknowledge a supreme being as creator and worship him, then there's only one available, so to speak! But if the Jews are worshiping the god who regards them as "his people", then that does complicate the issue. In Roman times, Marcion compiled a table of contrasting quotations from the OT and NT, to show that one promoted a "just god" but the other a "good god".
I think it's very obvious that Christians and Jews worship the same God.
I find it noteworthy that Jesus used the term Father, which was not used of Yahweh.
Again, you're ignoring the fact that God has different names in Hebrew, plus the fact that it was never interpreted as there being more than one god for us. If there were doubts, many other verses tend to verify that there's only one.
He also dismissed conversion to Judaism in his denunciation of the Pharisees, and said that Judaism was not the only way to heaven when he healed the centurions' son.
Jesus was operating as a Pharisee as was Paul. Nor does Judaism claim that somehow only Jews can go to heaven.
Needless to say, this view is controversial in traditional circles, although serious scholars have accepted for years that Judaism was created after Moses and Solomon.
Not exactly.
If one draws a line and says "Judaism started here", their line is arbitrary. For example, Abraham is called the "father of Judaism", largely because Torah credits him as being the first Jew who believed in one God, plus through God he established the Covenant for us that is observed by male circumcision on the eighth day after birth, and we are the only ones who have this as a requirement. Later, under Moses, we received the Law, all 613 of them, and we are the only people who try and observe them.
Judaism, like all other religions, was a "work in progress", therefore one simply cannot draw a line and say "Judaism started here". Names change, additions are made, people come and go, etc., but the basis of Judaism goes back far enough to the point whereas we lose it in antiquity.
Welcome to the forums here, btw, and I look forward to seeing more of your posts.
