You can read good translations of various texts, including the Book of the Dead, here.
As I said above, the shabti, the small (about 1-foot tall) figures that were found in many tombs were intended to be servants to help the deceased in the afterlife. Based on this, I make the educated guess that the Egyptians distinguished between real and symbolic. If they felt that way about servants, I assume they felt this way about other aspects of the afterlife goods. They were symbolic and for “display” - based on those around the deceased knowing what went into the grave. Plus, the stuff the gods found with you decided what you had in the afterlife.
So the goods were not so much “really needed”, as symbolic of the riches the deceased brought with them. Plus, it’s also possible it’s part of the “big swinging dick” theory - that your importance was demonstrated by the size of your … stash of grave goods.
Remember too, that the vast majority of the grave preparations from the time of the first pyramids onwards, were done over the years and decades before the person died. (with some pharaohs, you read "he died unexpectedly and the last part of the funeral preparations appear rushed.) So the pharoah had the time and enjoyment of being able to review and to boast about his funeral cache while he was alive.
According to one Egyptologist I asked, many many years ago, social pressure and even law required the ancients to put as much resources as they could into the funeral of a loved one.
Even today, you will find a reference to the “city of the dead” in Cairo. Even up to medieval times, the local funerals were still very involved and sometimes the family moved in to the crypt with the deceased for up to a month or more of mourning. As a result the fancier tombs were like small houses, with extra rooms, kitchens and ovens, etc. When an earthquake a century or more ago wrecked some homes in Ciaro, people moved into these unoccupied ready-made dwellings. Egyptian funerals were not the same as elsewhere, I guess.
What was the deal with mummified cats, alligators, birds, etc., placed in these tombs? I mean, having your pet buried with you makes some sense-why were all these other animals included?
My favorite in that category was the note by one of the animal mummies in the Cairo Museum that the animal “was mummified by means of a turpentine enema…”