From Warners Brothers to MGM, cartoons have always had a bias against cats. Sylvester and Tom are perfect examples of this bias. We'll start out with Sylvester. This is a cat who enjoys his home with the old lady and lounges through his day. The old lady then comes in and places a bird in a cage along the window sill. Tweety is left in the room with Sylvester, and then the old lady leaves. Now, Sylvester is a cat. He has instincts. His instincts tell him to attack the bird. Therefore, who is really at fault for the violence that follows? The cat who is only following his own instincts, or the old lady who foolishly leaves a bird alone with a cat next to a window sill?
Sylvester gets beat up by the bird, his "guard dog", and the old lady. He is often punished both mentally and physically for just being a cat or even defending himself from the visious dog.
Tom from Tom and Jerry is not as abused as Sylvester is, but the abuse still exists. He is often told by his owner to get rid of the mouse that resides in their home. Jerry sneaks into the kitchen, helping himself to cheese that does not belong to him. In an act to defend the home, Tom chases him down. Jerry often sets up traps such as rakes and explosives for Tom to faulter into.
Maybe one day some cartoon creator will come up with a cartoon cat that people will find a hero rather than a villian. But when you turn on the TV, don't expect to find any hero cats for now.