I don't believe this. Our cats will watch a cat on TV, but not a human. Our cats act differently to my wife and I than they do each other.
Cats have powerful senses of smell and use it for identification. We do not smell like cats.
Cats demonstrate competitive bonding with each other, but not with humans.
Cats use different vocalizations with humans than other cats.
Cats will observe human facial expressions rather than body language. They recognize we communicate with our face, not body.
All kinds of things. Cats may not know what we are, know we are potential allies (for the most part), but they also know we are not cats.