It was never written, it was compiled. There's like double the amount of books but the church cherry picked the books they wanted to include and ignored the ones that went against their world view. I'm the end it was put together for power and control. Even the fact that most people weren't even allowed to read it, meant that all the "laws of god" were being filtered to you through the church and whatever it was they wanted at the time.

To record their version of "truth." There was no distinction between fact and fiction, they were written to establish the "official" history with the political and religious (again, no distinction) agenda they wanted people to follow. The idea that history should involve accurate facts of what actually happened is a relatively new phenomenon in human culture.

Did the people of the time understand that nuance? I honestly don't know. I assume most of the uneducated masses didn't, which is why the elites wrote that way.

If you look at the dietary laws, the injunctions to monotheism, and the laws concerning sexuality and marriage it suggests that the prime concern was with providing the numbers to outcompete other nations, and I am using the word in its original meaning of an alliance of closely related tribes or clans. Israelite Nation, who are the people we have to thank for the Abrahamic religions, could see that it was a pure numbers game. If you could prevent food poisoning and other biological hazards and could also provide an extensive system of laws to adjudicate disputes without the need for violence within the tribes, then you could get everyone faced the same way. You had a growing population so that once the warriors killed the neighbours you could then quickly settle and colonise with the civilian contingent who could then produce more supplies for ever bigger military campaigns.

The many different books of the modern Bible were written hundreds of years apart, had many different versions of the same 'book', existed amongst many other 'books' that are now apocryphal or just totally lost to history, and were of many different genres, written in different languages.

This is like asking 'what was the strategic purpose of the entire history of the kingdom of Spain'.

New Testament: Given that the bible, as we know it today, wasn't assembled into its current form until hundreds of years AD...

While being written, it wasn't being used as anything other than a record of events. Given that most of the events recorded in the Gospels happened decades before they were written down, they were effectively turning oral tradition to written tradition. The later books in the new testament, excluding Revelations, are largely letters traded between early churches.

Revelations is where shit gets weird. A bible without this would be far superior, harder to weaponize, and probably would be considered a living corpus rather than a fixed thing. If there was intent when writing anything in the bible, it was here. And here is where we can start arguing nefarious intent, turning the religion into a death cult.

It was a written down collection of oral traditions and laws, so I guess the purpose was to get it all down in one place so people wouldn't have to keep remembering it and passing it down that way.

Control.

Depends. I'd say giving identity to a group of people applies to the whole bible. Other than that, the bible consists of various books from different times. Especially the New and Old Testament have been written in widely different environments, for different purposes (and they're both collections and not written consecutively by one person).

The Old testament is telling history and heritage of a tribe. (Sometimes with made up stories. Because the point was to hand down a good story so people "know" where they come from and how ther relate to other things in the world.) Giving them identity as a group. A lot of that has to do with tribalism. At the same time being god's favorite justifies slaughtering and robbing other tribes. (Still applies as of today, by the way...)

The New testament is a bit more complicated. The world was more complex at the time of the Romans. And it's been written by several different people who did not even live at the same time. I mean there are lots of things in there. It's about salvation, ideas about ethics, it's a collection of nice/random stories, sometimes someone retold them or put their own spin on things... And it's also not factual or anything like that. Though I think some of it mimicks telling the tale of some figures of history. But it wasn't ever a book about history. It's always mixed with fiction. We have proper records because the Romans kept records. While all of the bible hasn't been written at the time of the events, but it's more writing down stories that have been handed down and retold several times to the point where they don't really depict reality. Or they're straight made up for some motivation. Or continuing some narration from earlier authors.