See explanation:
Step-by-step explanation:
1) In movies that include animals, its not always possible to get real trained animals or even untrained ones to behave how the directors want them to. So CGI enables non-human characters to act the way we want them to.
2) In fantasy movies, we know that almost all the things are not scientifically possible. And due to that, its not possible to create such fantastical scenes in real life. CGI allows us to bring human imagination to life, even though its scientifically imbossible.