Why are dogs and cats the most popular pets?

I think it begins with the fact that dogs were solely domesticated by humans which is the reason why people tend to own one rather than rabbits and monkeys.

Rabbits aren't keen on interacting with humans. Cats are loving but full of personalities. Monkeys are rather independent that sometimes humans don't entirely understand where they are coming from with their energy. A goldfish would be nice but you can't pet him and it's a lot more difficult to train them (but this is possible).