Spot on Cyberjesus ! all we have is some 3rd Century and later manuscripts that are copies of copies of copies ,and some of those are translations too !
We have no way of knowing what the original writers put down for sure, and even if we did have autograph copies, we would have to take in to account the writers agenda, his motive, when it was written etc etc . The latter we can do a lot of, just as an example, many scholars feel the "Matthew" was written , at the earliest around the late 80's or 90CE, so, why write as though it is before the Temple destruction ? (Agenda/motive)
Study of the Bible is fascinating, as is study of many ancient texts, see Leolaia's excellent posts on this over the years, but however clearly one comes to understand the writings we do have,( and the modern translators own theology may get in the way see the very poor NWT !) we can never claim that we have a text that is reliable enough to argue about every "jot and tittle" , and certainly to be dogmatic on any point of doctrine based on such poor source material is to make oneself look very silly.