Well it was sticking with your analogy.
It pointed out that if a cat (zombie) doesnt look like a cat, doesnt act like a cat, doesnt smell like a cat, its not a cat....it might be something else like a fish (Rage infected living human).
Theres only so far you can stretch a definition of something before it becomes something else.
It was pretty good... I did feel it started going down a bit along the way. I felt that our main character found his family way too soon. They could have let that strand last for one or two seasons.
Plus I thought they ditched the guys in the city protecting the elderly way too soon. So a tad sketchy. Episode 1 was classic though. Hope season two picks up.