Why is the speaker a skeleton?

To me, the speaker in this poem is a skeleton because he
is supposed to be representing people who have been dead for a long time.  This is
because this is a poem about how people never change.

The
major theme of the poem is the idea that people in modern times are just as warlike and
violent and awful as people always have been.  So it makes sense to have the speaker be
a skeleton that has been dead a long time.  This speaker can sort of "wake up" and say
"wow, how come things haven't changed in all the centuries since I
died."

So having a skeleton narrate helps to make the point
that the poet is trying to make.