Extraterrestrial monsters destroy humanity, save for an obstinate survivalist who vows revenge.

Seems like the story could parallel Planet of the Apes, where the survivor must find some support from disenfranchised aliens and wage a counter offensive. Being a survivalist, he has pretty much already met his goal: he survived.

Very true.
This is in part why I originally suggested to give the MC a grand goal of stopping the aliens from doing this again. This way despite the lose of humanity there still are great stakes at hand.

>>he's forced to fight, or risk discovery.?

Only discovery? Not death?

And if as the original logline suggests, the survivalist is indeed the last homo sapiens, after he wreaks revenge on the aliens -- what good will that do? Mankind is doomed to extinction anyway.

Bummer.