No. cats is smarter than dogs..
so cats make better companions than dog. = No. Cats are smarter than dogs and that makes them better companions than dogs.

many human think dog is smarter than cats. = A lot of people think dogs are smarter than cats.

this is my idea. = This is only my idea.

my idea is not truth. = It doesn't mean it's true.

cat is smarter than dog. = Cat is smarter than a dog.

cat is only selfshness. = Cat is only selfish.

cats is not stupid. = Cats are not stupid.

cats don t follow the human. = And cats don't just follow humans around.