A Believer, now I believe you are indeed truthful when you claim you only recently took up researching JW doctrine.
Reason I say this is that its basic WT doctrine that all JWs know. The JW teaching regarding the Great crowd is that they are those that associate with the WT (otherwise known as JWs) that survive Armageddon and live in paradise Earth (btw, the term "paradise earth" never appears in scripture anywhere).
The fact that you automatically assumed the Great Crowd was indeed in heaven should point to you that it is an easy doctrine to reason from Scripture. Yet, the WT still teaches something contrary to this easy reasoning.