By "Our current canon" you mean "your particular view of the canon according to your church". I understand that your canon is paramount to you and maybe the correct one, but you must also understand that others have other canons and
they could be correct too. Unless of course you have done extensive analysis and identified "your canon" as the right canon.
Isaiah having 66 chapters doesnt mean anything. In that case the book of
Leviticus has 27 chapters. Your NT has 27 books.
Joshua has 24 chapters, and the Tanah of the Rabbinic Judaism has 24 books. So does 2nd Samuel have 24 books. Just that you should ask the Jews if Samuel has 1 and 2 or not.
Yes, these are all coincidences.
The Old Testament does not have 39 books (Protestant Canon). It has been made to look like it has 39 books. I am not a Jew but the Jewish faith has 24 books in their canon. Christian church has taken the latter canon known to them as the septuagint for their text and that should be from the 3rd century. But if you truly wish to go to the Old Testament deeply i believe that you must go to the Jewish tradition because thats the oldest and more authentic
tradition when it comes to their own scripture.
And of course, reason.