That's not the point. The point is that there wasn't a single canon, different sects of Jews had different canons. All these canons were overlapping – all Jews accepted the Torah, there was widespread (but not universal) acceptance of the Prophets; the third part of the Jewish canon, the Writings (Ketuvim) saw the most disagreement. And we have evidence that the canon of the Qumran community did include books now considered "apocryphal"–see https://www.jstor.org/stable/24663170

Did some Greek-speaking Jews include "apocryphal" works in their canon, just as the Qumran community did? Well, we have evidence that the Qumran community included Greek-speaking Jews – most of the Dead Sea Scrolls were in Hebrew or Aramaic, but some Greek texts were recovered as well.

We know that many Greek-speaking early Christians accepted some of the pre-Christian Greek "apocryphal"/"deuterocanonical" works as canonical. Why did they do that? Well, a very plausible hypothesis is that some Hellenistic Jews already accepted them as canonical, and Hellenistic Christianity inherited that acceptance from (segments of) Hellenistic Judaism. We don't have direct proof of that, but as a historical hypothesis it is very plausible, especially in light of the evidence from Qumran that some Jews (even Greek-speaking ones) did accept (other) "apocryphal" works in their canon.

> And that's besides the fact that even if there was some so-called "debate" about it, if the canon didn't actually change as a result of those debates (e.g. Song of Songs and Eccl. are part of the canon), then how can you say it wasn't fixed?

The canon did change. In the middle of the second century CE, the Pharisees still had multiple canons – a narrow canon which excluded Song of Songs and Ecclesiastes, a broad canon which included them, and also a couple of intermediate canons which included one but not the other. The outcome of this debate was that the broad canon won out over the narrow and intermediate ones, and supporters of those other canons died out.

And, if we consider other Jewish groups such as the Sadducees or the Qumran community, we find even more Jewish canons than that. However, the 1st and 2nd centuries CE saw a great deal of decline in the diversity of Judaism, due to various factors (the trauma of the Jewish-Roman wars, competition from Christianity), and part of that decline in diversity was the reduction of multiple canons to one. But that reduction did not complete until after Christianity had already split off from Judaism, which is why many Christians (both in the early Church, and also today) do not believe that Christians are bound by it.

And why do you dismiss it as 'some so-called "debate"'? It was a real debate, you can read the Mishnah for yourself – https://www.sefaria.org/Mishnah_Yadayim.3.5?lang=bi&with=all... – allow me to quote some of it:

> All the Holy Scriptures defile the hands. The Song of Songs and Kohelet (Ecclesiastes) defile the hands. Rabbi Judah says: the Song of Songs defiles the hands, but there is a dispute about Kohelet. Rabbi Yose says: Kohelet does not defile the hands, but there is a dispute about the Song of Songs. Rabbi Shimon says: [the ruling about] Kohelet is one of the leniencies of Bet Shammai and one of the stringencies of Bet Hillel.

All the Rabbis it quotes are known to have been active in the 2nd century CE. So in the 2nd century CE, there was a real debate among the (successors of the) Pharisees about the canonicity of Song of Songs and Ecclesiastes.

Furthermore, this passage gives evidence that the same debate was active in the 1st century CE as well (and possibly even the 1st century BCE too), through Rabbi Shimon's reference to Bet Shammai and Bet Hillel.

You're attaching a lot of weight to a lot of different historical viewpoints. Of course you can find different sects of Jews with different canons. You can find different sects of Jews doing a lot of strange things including committing mass suicide.

However, the majority of the most recognized scholars and historians of the first few centuries C.E. do not consider the so-called apocryphal books as part of the Bible canon. Josephus, Jerome, Councils at Laodicea and Chalcedon, as well as numerous church Fathers (e.g. Justin Martyr, Melito, Origen, Hilary, Epiphanius, Gregory Nazianzus, Rufinus of Aquileia) testify to the closing of the canon outside of the apocryphal books.

> We know that many Greek-speaking early Christians accepted some of the pre-Christian Greek "apocryphal"/"deuterocanonical" works as canonical. Why did they do that?

It doesn't matter. A lot of your arguments hinge on finding obscure debates and controversies. So what if there was controversy among some? The general consensus, however, disagrees with those debates and controversies and finds them irrelevant.

> The canon did change. In the middle of the second century CE, the Pharisees still had multiple canons

You mean the same Pharisees about whom the the Jew, Jesus Christ, said: "Thus you nullify the word of God for the sake of your tradition." (Matthew 15:6)

> And, if we consider other Jewish groups such as the Sadducees or the Qumran community, we find even more Jewish canons than that.

Again, do you mean the Sadducees whom Jesus and many first century Jews condemned? It's irrelevant to even consider any canon that contradicts the most well respected historians and scholars of those time periods. You refer to them as "canons" but they are no such thing. The Hebrew canon was well established by the time of Josephus and only a few obscure sources contradict that.

> And why do you dismiss it as 'some so-called "debate"'? It was a real debate, you can read the Mishnah for yourself

I dismiss it because it's irrevelant. In fact, it's about as relevant as you and I having this debate right now, because neither you or I can change the fact that the canon was well established before the 1st century CE.

> All the Holy Scriptures defile the hands.

You want me to take seriously a document that says that?

> Furthermore, this passage gives evidence that the same debate was active in the 1st century CE as well (and possibly even the 1st century BCE too), through Rabbi Shimon's reference to Bet Shammai and Bet Hillel.

Yes, it was very active -- among people who had no say in the matter and whose opinions didn't mean a whole lot until we decided to throw 20th century criticism into the mix.