>Christianity predates the Bible

In the sense that Adam and Eve were Christians, sure. But if you're suggesting the Bible was created by the Church, your own councils disagree with you. Vatican I explicitly condemns what you're trying to say. The Church is a witness to something that already existed, nothing more.

>Additionally, the original KJV includes the deuterocanon

I know, mine does too. It has books that the Council of Trent removed, like 3 Esdras. Why would the Pope remove books from the Bible?

>My point stands that KJVOnlyism is a subset of Sola Scriptura

They literally aren't the same thing. They're two completely unrelated claims. I'm also not a strict KJVO in the way someone like Steven Anderson, but it's undoubtedly the most important English version, for more reasons than you can count on one hand.

I make it a point not to argue sola scriptura. Not because it's wrong, understood properly, but because people on both sides refuse to understand it properly, so it's a useless hill to die on.

>The Latin never changes

Buy a critical edition. It does. You have old Latin, and tons of variation within the Latin tradition, often referred to as the Western text type. It's actually famous for being the most inaccurate text family that gets any serious consideration.

In current day, Latin editions have the exact same problems as modern Greek critical texts. Though an Old Vulgate only position will get you better results than following modern text critics, due to the nature of what a translation is, it's inherently inferior to my position. Eastern Orthodox have it better, they have their own version of a Greek Received Text that's different from ours, although on internal analysis, it doesn't hold up as well. Romans has a false ending after chapter 14, for example. It's also missing the Comma.

>that full translation predates the Canon

Roman Catholics really need to read the studies of Roger Beckwith. This idea is disproven. The Old Testament canon was decided 200 years before Christ was born. The fact that later Christians (and some jews) were misinformed and got it wrong does nothing to disprove this. Although most of the early Fathers actually do agree that the canon is only 22 books (by the Hebrew numbering) so no matter how you look at it, the Roman Catholic theory of canon doesn't hold up. Nevermind the blatant historical errors in the books.

>Original manuscripts of Greek, Aramaic, and Hebrew are not always available, so when they aren't we always have the Latin.

The Latin is better than nothing, but once printed editions become a relatively affordable thing, there's no reason to use it as a primary source anymore. It has a lot of problems.

>"biblical study" is not Christianity

It's literally the word of God. It doesn't encompass the entirety of the Christian life, but you can't have orthodoxy without it.