Humans having any kind of sporting chance against hostile alien invaders armed with superior technology - Good luck. If they're advanced enough to cross the enormous distances of interstellar space, they're advanced enough to wipe us out without breaking whatever in their physiology passes for a sweat.

Human divisions would be child's play for any reasonably competent alien overlord to exploit - check the masterful 'Twilight Zone' episode 'The Monsters Are Due on Maple Street' for an example of how that might play out.

Beyond 'Contact,' I think there's something compelling about 'District 9.'

Nick Sagan Quotes