Yes, you have your work cut out as soon as you get to the 1st Century for sure. Although as with a lot of this, we cannot be categorically sure as to what happened, and who wrote what, etc we can say with assurance that things were not as most people viewed them up until the Enlightenment, and as some still do, that the Bible is inspired and accurate for a start, and written by who it says it is etc etc
The other big myth, perpetuated by other religions as well as JW's, is that there was one Pure Church which sprang up after the death of Jesus.
That is far from reality, there were a good number of different groups that claimed Jesus in some way, all teaching different things, the Bible itself tells us this. Even what we call "Pauline Christianity" is an amalgam of teachings, some from Paul and some adapted after his death by writers pretending to be Paul.
Then we have the intervening mess of battling ideas that was sorted by Constantine because he had the power to do so. Many things were not fully sorted, the Trinity debate continues, the ideas as what is "Canonical" and what should not be included as Scripture goes on too.
If the Christianity of today were claiming to be a valuable antique Vase for example, the experts would say " This Vase has no Provenance".