Funniest part is: they can't even agree internally on how to believe

I view it as slightly better than that interpretation. The Old Testament is what links the three. The interesting thing about the Old Testament is that it was written over a few thousand years starting around the time of two major historical events that could have precipitated what would look like a potential "apocalypse," to anyone at the time.

The Green Sahara period had just come to an end, denying Egypt what I would imagine was a substantial breadbasket for the Egyptian, and possibly Assyrian Empires. That event may not have directly caused The Bronze age collapse, but they happened quickly enough together, that I would imagine it was a factor.

So in a period of a few hundred years, a savannah that had plentiful game and foraging turned into the largest desert in the world. The Levant went from a seemingly temperate mediterranian climate, aka "the promised land," to a desert mediterranian climate. All the empires that you know of just collapsed in a period of 150 years. You might just get a bit superstitious, and borrow some ancient creation myths to write down the "history" of your people.

Lots of cultures did this. We know from archeological evidence that the Israelites weren't ever in Egypt, so everything up to, and including Moses, was made up to try to teach their descendants how to live in this new horrible dying world. It's just absolute random chance that the Israelite texts survived long enough to spawn the other two belief systems.

in my personal edgy opinion, religions are a cope & a great tool of control.

They give you hope against the biggest fear ingrained in us - death, and even worse - death being equal for everyone, good person, bad person, both will die. It's a nice thought to believe that there is fairness to it all, that good actions should be done despite bad actions being easier. It's a nice thought to believe there is something else after you die, and none of your good (or bad) deeds go unnoticed, that you, a good person, will live in paradise, and your enemies will finally suffer the consequences of what they've done.

it also helps bring people together, creates a unified peoppe and a culture of those who believe in the same thing & allows a potential leader to have an easier time rallying everyone towards the same goal.

religion is a wonderful tool for both coping with existential dread, and unifying people. but as a tool it has the capacity for explaining away both good and bad things quite equally (helping poor, crusades, personal growth, bigotry).

what relgion is based on is close to irrelevant, it just has to be something, preferably a good overall story with many smaller stories that teach the common folk how to be a good [insert religious identity]. Try reading ancient Egyptian mythology, i suspect most of that shit was written on heavy doses of psychedelics, and despite how completely insane all of it is - it unified people and was an integral part of the biggest empire of the ancient times.

honestly i don't want to "debunk" people's religions, if it's something that keeps them going then why take it away, i personally tried but failed multiple times at believing in any god, but i can't lie the existential dread of "one day i will die, no matter how much i managed to achieve, no matter how good of a person i was, i will die the same as every murderer or war criminal, and there will be no justice in that, and then, one day my name will be spoken for the last time, and i will be forgotten" is a heavy thought to bear, no wonder that as a species we've always tried to find some reason, any reason, for that not being the case