I was looking into the history of the pyramid and noticed that there are shafts in the King's and Queen's chambers. Archeologists haven't been able to learn the purpose of these shafts and all they found at the end was slabs with copper handles behind which there was a ball of black diroite stone.
What is the most likely explanation for this?
The shafts were mostly likely used to connect the burial chamber to the outside world so the King and Queen's soul could escape into the material world and return to the body at will.
One of the five Egyptian souls was the ba and was typically represented as the head of the deceased on the body of a falcon or other bird. This soul would probably leave the pyramid via the "air shaft" as you put it, and return to rest in the mummy when the day was done.
Other, smaller tombs would have much smaller openings for the soul, but on a massive pyramid the shaft would have to extend from the tiny burial chamber in the centre to the outside of the structure.