The first person known to have asked what happened to Mary's body was St. Epiphanius. He was a 4th century Bishop, close to the scene of events,
So the first time anyone bothered about Mary's death was 3 or more CENTURIES after she died. And this is called "close to the scene of events". He's no closer to scene of events than I am to the scene of the American Revolution. In fact, I am closer to those events; should I start claiming to be an expert?
Have you considered WHY nobody worried about figuring out how Mary died for such a long period of time? Could it possibly be that Mary is not central to the Gospel message? Have you considered the timing surrounding the emergence of Mary as akin to a goddess?
There are reasons why the "Assumption" is not in the Bible: (A) Mary is not of critical importance to the Gospel message; and (B) It never happened.
Should read 2 or more CENTURIES