it's petty clear to me that ALL of Christianity is a sect of Judaism

Yes, that’s how Christianity happened. A bunch of Jews believed that when Jesus claimed he was a son of God, that he was telling the truth, and his crucifixion and subsequent resurrection rather solidified that belief.

But not all Jews agreed, so those who did believe in the divinity of Jesus Christ became known as “Christians“ over the next couple of centuries.

So, yes, Christianity can be viewed as a particularly peculiar sect of Judaism

Yes, Judaism, Christianity and Islam are called Abrahamic religions for this reason. They're the product of the same lore in different eras.

I would argue it's more of a sequel or reboot. Jesus even talked about keeping the law and such, which arguably defines a lot about Judaism, but you'll find almost no modern christian sects that do.

Yeah, but Christianity pretty much invented antisemitism, and our Christianity as we have it was likely much more influenced by Greek speaking gentile communities in Rome and Asia Minor than by the early Jewish Christians.

I am not a scholar, but my current thinking is that the Jewish/Petrine Christianity started by Jesus’ disciples largely disappeared and is attributed to an early christian sect called the Ebionites. What we have today is largely Pauline and Roman by descent.

Judaism is not generally trying to convert the masses.

Christianity is inherently more dangerous because it is both exclusive and evangelical.