This App Inventor advice will help Creating Animated Apps as will the advice here Issue with first point and click "adventure" game (how to make decisions) .
Use an App Inventor Canvas with AI. Canvas is similar to what is used in Scratch. AI and Scratch have 'similar' Blocks. Unfortunately, you must create your own blocks following the Scratch logic. There is no Scratch to AI conversion program. There are similar coding Blocks. Do you know how to code in Scratch? If so, read the free ebook mentioned below and it will help you get started with App Inventor.
It is possible you can use some of the resources in the Scratch project in your AI Project.
Regards,
Steve