I was between the last remaining, and always alone, so I picked the former. I mean, what is their to gain if you can find alien objects, but learn nothing from it? It would be the same as learning about the dinosaurs--of how such other great creatures were wiped out by some force, therefore meaning we have the same fate? We would have to die eventually, leading unto my next point.
And, with that inevitable end, humans would be the last life. If we were to die out, there would be no more life.
Permanently.
Think about existence with no one to know about it--the tree in the forest that no one hears. Time would be irrelevant with nothing to keep track, as the vast planets and intergalactic bodies have no sentience.
In that idea, it would be frightening to know that we control the entire spectrum of life itself. And knowing how careless and wasteful humans get when they have power and vast empires, the future would have thousands of ways to put itself to the dust.