So far as I can tell, there are only 2 "JW-unique" teachings that have remained the same in the vast wilderness of WT teachings (and I mean the beginning of the beginning, going all the way back to Russell):
1) No Trinity
and
2) No Hell (at least, not as a place of eternal torment).
But if reliable truth can be determined by its enduring and unchanging nature, why does any of the other stuff matter? It's all trivia in the end. The problem is, with just the above "truths" as your yardstick, well, shoot - Unitarian Christians, Christadelphians, and many others would qualify as "true" religions. But the WT can't have that, now can it?