Earth is the central research lab of the Universe. This is the place everything gets tested. Now you know what your purpose is?

A smear that is examined under a microscope, evaluated and reported to "the powers that be" who reside elsewhere.

How does it feel to be a test sample? You won't know the results of course. Was what you were being tested for a win or a loss? A keep/save or a dump? At least you know you have been useful. That is enough.