You can simply describe your product/app with a dry feature list. Better: you can use case examples to show how things work in practice. The best approach: use one case example/story throughout your entire presentation:

• You can go into a bit more depth to set the challenge your product tackles
• You do not need to reintroduce the case example all the time, we already know the full background of the main character in your story
• You can show that your product can be used on multiple occasions at different times of the day
• You can also introduce smaller features using the framework of the overall story
• You can instantly create a consistent look and feel across your presentation