The Dead

I was confused at first. Death was only thrown around at the beginning seemingly haphazardly. It was only mentioned, but when the final parts came, death and lots of thoughts of death/the dead came up very quick. I'm still confused with the characters and the focal points and why all of the beforehand is necessary, especially when the ending seems to be the only real important part. I don' believe that many of the other characters where necessary for the ending which is why I'm curious as to why they were even included/who they are.  Lily and some of the guests, for instants. Joyce went into detail about many of them, yet by the end it seems that only a select few are even mentioned.