She is the first of all the people God has created to receive her resurrected body, and as such she is a sign and promise to the rest of us that we too will arise and receive a renewed body. The separation of body and soul is a product of death not Life.
The question of whether Our Blessed Mother died before she was Assumed remains unanswered. However, it seems from the tradition of the Church (both East and West) that she did die first. Her tomb was in Ephesus, although the sarcophagus has apparently been moved to Gethsemane now.
Some people have suggested that she didn’t need to die as neither Enoch not Elijah died. However, I think the story of the two prophets who will return to herald the Second Coming is a bit different. The prophecies about these two returning say they will die as martyrs then and be raised again three days later.
As Christ died, who was without sin, so it is fitting that His mother, sharing in all He does should also die first. In the East they have called this “falling asleep” which is a beautiful way of saying she wasn’t claimed by death but was then given the gift of full resurrection by her Son and taken to heaven.
Christ spoke against the Sadducees who denied the possibility of the Resurrection, but they didn’t listen (apparently). In His treatment of Our Blessed Mother, He offers a proof of the Resurrection that awaits us all. I think there are even Christians who deny the possibility, so this is a good reminder.
If you want a better explanation of the Assumption – watch Dr Scott Hahn.