I'm planning on running a custom campaign with a bunch of friends and the gist of it is that Earth got destroyed by dickish bureaucratic aliens that bought Earth many thousands of years ago before it actually began to seed life. Of course Earth got buried under so much bureaucracy that the aliens promptly forgot about it and went off to do other things, like conquering their neighbors to increase product induction by 10%.
Did I say they are not nice people?
Either way Earth gets destroyed, but the human race isn't extinct as the aliens were "kind enough" (read: forced) to at least ferry some of the humans off planet so they can propagate elsewhere, or something. Either way the last bits of humanity (only about 500,000 humans from about 9 billion) got loaded up on these cargo ships of various sizes and qualities and kindly told to go elsewhere.
If things were only so easy, that is...
So yeah, the PC's start as humans but they can be other races later as they convince other species to join them either as sympathizers, lovers, or simple crewmen.
Also plenty of custom races using the race-builder.