I have a theory that zombies fascinate us because they are a reflex to our Darwinian fears.
Most zombie flicks center on some virus, man-made or otherwise, infecting people. From the days os Pasteur on, we have prided ourselves on beating Nature at its own game but a zombie virus is A) our pride in our accomplishments turned to self-destructive hubris or B) reminding us that our vaunted knowledge is not complete and we are merely one jungle trek away from nature's last surprise.
Worse, the zombies have been robbed of their intellects, reduced to maddened creatures. No more higher concepts of beauty, science, art, love, justice...just raw, clawing animalism. Not even the bonds of family survive.
Then, as the plague progresses the civilization humanity built to fend off wars and raw brutality succumbs to an ever-increasingly brutal war against brutal forces. The decline is slow an inexoriable. Civilization was supposed to be a darwinian reflex to the need for survival and in it man grows accustomed to every vice: sloth, gluttony, cowardice, etc. Yet, when the hordes arrive his vices prove to be little more than petty lapses of character when true, existential nihilism threatens and he must shed his vain comforts for the bloody scratchings of moment-by-moment survivalism.
Yet, as portrayed by the survivors, man would rather be hungry, naked, fearful and merciless than surrender the last vestiges of his conscious soul. In the contest between being and non-being man defies. in philosophical quarters there is the doctrine of Buridan's Ass, a mule that finds itself equi-distant between two equally appealing stacks of hay and it would starve. The only thing that would save it is an act of Will. From this many deduce the existence of God, that being from Whom all existence descends by act of Will though existence itself could equally not have been. Thus the protagonist whispers the very nature God in his very act of struggling on to the next scene. In the struggle between being and non-being, Being must Be in, of and for its own sake.
Or is it just good brain-splattering fun?