Questions on the historical existence of Jesuss are off-topic. Why don't you start a thread on that subject?
There are over 45000 Christian denominations worldwide
Most are just different flavors. Most are congregation led. That way heresy is contained locally when it arises.
Not many churches disagree on how to get saved, the ones that do are cults.
When a person has a reprobate mind, they can no longer read the Word of God and understand. They could read something very similar in another book and have no trouble understanding.
There is no problem understanding this verse for a person whose mind hasn't been ruined:
And he took the cup, and gave thanks, and gave it to them, saying, Drink ye all of it; For this is my blood of the new covenant, which is shed for many for the forgiveness of sins.” - Mt. 26: 27–28
Very simple, as is this:
“God made him who had no sin to be sin for us, so that in him we might become the righteousness of God” (2 Corinthians 5:21).
Anyone reading these verses gets the idea that Jesus wants to take your sin debt off of you and place it upon himself so that he can die in your place.
God spent spent 1500 years to try and get people used to the idea of substitutional atonement in the Old Testament. If you have a reprobate mind, God could spend an eternity trying to get people to understand it and it still wouldn't matter. They would have no trouble accepting the concept if read in another book though.
The bottom line is that JW's and people in general really don't want to be saved, because they are depraved. They don't want someone else to cover their debt which requires the death penalty. Most don't even acknowledge that they have a debt to pay, although they hypocritically require payment from others when they are sleighted.
These kinds of folks want to earn Salvation so they can protect their illusion of righteousness, rather than be transformed into it.
The Ransom-For-Adam spin that the WT sells is an attempt to explain away Jesus sacrifice as something other than a substitutional atonement "for each of us" and protect peoples secret desire to justify themselves. This of course is unacceptable to God and is very rude because God clearly states that:
"BY THE WORKS OF THE LAW SHALL NO FLESH BE JUSTIFIED" - Romans 3: 20
Personally, have no idea why God would want to save ANY of us. I speculate that believers will be fit creatures to properly love him and increase his joy and quality of life one day.
But why would God want to spend eternity with someone with a broken mind who can't even receive a free gift, someone who requires justice from others but not themselves?
Who would want to spend an evening with someone like that? ... much less an eternity?