All of the discussion on this thread assumes that if a) There are aliens and b)They are here and c) They want to contact someone that ..... they'd contact us. They might not even look at us as life forms.
Sagan's ants on an anthill analogy from Contact comes close to this as well. A life form, but worth communicating with?
There are lots of other possibilities as well. They're out there, but they've all discovered just how dangerous the universe is and have shut themselves up inside their own Dyson spheres and are intentionally hiding, lest some other beastie finds THEM. The ones who survived, that is. The ones (like us) who sit there, radiating out a "we're here" message get to do that for around 100 years. By that time the Vogon's see us and come read us some poetry. Fini.