No - The major pyramids on the Giza plateau date to c. 2500 BCE (within a 75 year period) - and were built by organized teams of contracted Egyptian labourers from all over the country working in 2-3 month shifts. In 1990, Dr. Mark Lehner and Dr. Zahi Hawass discovered a large workmen’s village on the plateau where workers were housed, fed, cared for if injured - and even given respectful burials.
No-one can be certain who - but it was not Napoleon’s men using it for target practice. Most likely it happened between 1600 and 1750. We do know it was pried off using iron rods -- as there are boring holes apparant just over the nose and near one nostril.
The exact cause of death for the boy king has never been fully determined. However, he was a very sickly lad who suffered from a great number of ailments including malaria and a club foot. Dozens of canes were found in his tomb.
The answer can be long and complex -- and we do great lectures on Mummies. The short answer is that in order for their spirit to transform to an “akh” (an effective one) and enjoy an afterlife it had to be able to return to the tomb and recognize its intact body.