Bible Quiz—it's fun and challenging

[Aractus]

Most of your hyperbolic phrases (e.g. "no serious scholar") amount to saying "in my opinion."

No it doesn't, it means that among all the scholarly differences in opinion between believers/unbelievers, etc, that there's a clear consensus view on it and that most hold the view - in this case - and it is indeed near-unanimous that the LXX was written in stages by different translators, it was never a single volume of work written by a single person or company at one time. The books were translated decades if not centuries apart, and so calling "it" "The LXX" or "The Septuagint" is in fact incorrect in the sense that it presumes that it was a single volume of Greek when in fact it wasn't, it was a collection of translations made at various times from c. 1st century BC to 2nd century AD, and we don't have the original either. All we have is a copy of the fifth column of the Hexapla, and it's widely acknowledged - and here's that term you didn't come to grips with before - it's a near unanimous view that Origen made changes to it as he went along, the changes were largely based on other Greek translations of the OT which had been written in the 2nd century AD, and also to the Hebrew itself. Outside of certain Biblical quotes, there is no evidence for the LXX's existence prior to the Hexapla. Origen was a Christian, he had the New Testament texts, he could have changed those parts of the fifth column to align with the small handful of quotes from the OT that favour the LXX.

I don't think that he did mind you, I think that "the LXX" was not "completed" until the 2nd century, that the Pentateuch was translated in the 1st century BC, and that the Prophets were translated 1st BC-1st AD centuries, and that the Writings were translated 1st-2nd AD centuries. All by different people, and then collected together.