hell yes, starcraft ripped out Aliens vs Predator, blizzard should be blown up by an atomic bomb and everyone who bought starcraft should have their genitals cutten off and force them to eat it.
there might be an influance, after all, everything gets a little bit influance for another everything. when you draw a warrior, you add a weapon a shield, when you draw a orc, you make it warcraft-ish. influance is a share of idea and a loss of creativity, but the mix of influance and a new idea makes creativity.
for the zerg, i say coincidence, it's something common that aliens wishes to annhilate the world. and don't forget blizzard have many ideasman and history writers, so they're way superior to us in this domain.
anyway, i never seeen A&P, but i do think stararararararacraft have a unique storyline, like warcraft ( especially the kil'jaedan's offer to nerzhul for him to be a lich king or suffer for eternity )