It would be extremely naive for anyone to deny that the Watchtower does have a clergy class. This is understandable since the rank and file are persistently mesmerized into believing that they do not. However, although the rank and file deny it, the Watchtower leadership THEMSELVES admit that they do have a clergy. Should anyone fall foul of the leadership and has need to sue them, he will promptly be told that "clergy priviledge" protects all Watchtower Followers who are professionally inducted into the movement. If you earn your living, no matter how much of a pittance, from the coffers of the Watchtower, you are regarded by the Watchtower as a member of its clergy.
It is also impossible to "prove" that first century Christianity was led by a secretive, largely anonymous group of self serving men called a "Governing Body". The expression is found nowhere in the NT, and considering the fact that Paul had so many clashes with them, the possiblity is reduced to pure fiction. The text that the Watchtower suggests as a prop for this doctrine, Heb 13:7 [especially as a ritualized footnote in the Bible with References edition] wasn't written until about 65-69 AD, almost a generation after the start of the Christian Church in 30 AD. What did the early Christians do till then? How could they endure a doctrine of a "Governing Body" before it had actually been revealed?
If the early Christians had a "Faithful and Discreet Slave" class BEFORE 70 AD, when the first fulfillment of Matt 24 was to take place, then who were they? Were they ALL "anointed" Christians? Women were as "anointed" as men back in the first century, weren't they? So, did the FDS include women who supplied this "food at the proper time" thus effectively teaching other Christian believers? Did Christian women go from door-to-door back in the first centiury? This would be particularly strange given that women NEVER called privately on anyone, unless of course they were soliciting business of a questionable kind!! Note that EVERY illustration that the anonymous Watchtower writers provide, shows MEN only doing this activity.
It would be difficult to show that first century Christians met in "Kingdom Halls", when the NT indicates that they met regularly in private homes. There is certaily no evidence to show that they observed the "memorial" of Christ's death only once a year. Indeed their approach to this was to observe His Resurrection as a living Saviour, not His death.
On balance it must be added that every cult believes it, and it alone, is the exclusive inheritor of the first century Christian legacy, and all make the same grotesque claims that the Watchtower does. Some claim that the early Christians spoke in tongues so modern Christians should do so, which then becomes a mark of exclusivity. Some claim that Sabbath observance was a vital link in the chain, others that the keeping of the original Jewish feasts such as Passover, Tabernacles, and so on, were symptoms of this continuity, and on and on it goes.