you still have to take into account the concept of "countables and non-countables"
Let's take chocotate.
My favorite sweet/candy is chocolate/toffee/nougat. Because chocolate is not countable, you can weigh it, you can talk about "a piece of chocolate" " a kg of chocolate", but chocolate itself is not countable.
Then you also need to think a bit about the difference between "things and types of things".
So the novel is my favorite book, sort of works, but really it needs to be "the novel is my favorite type of book"
Then 4&5 just do not work as your structure and your examples are at odds.
So, "my favorite animals are dogs and cats" but "my favorite type of animal is the dog"
Hope that helps