I was just wondering and correct me If I am unable to understand your question correctly.
You can do this without using a Page Type. You can also you a custom table and define your fields for a slide. Adding one more slide will be adding a record in a Custom Table.
What you have asked for is possible in Kentico using Custom modules that allows you to create M:N between records. I am unsure if it is needed here unless you want to create multiple Carousels.
So you can opt for Custom Tables instead of Page Types. We do that when we don't want to pollute content tree and Kentico has repeater for CT also.
Bonus: - Use Ken Wheeler's Slick slider library which is the best library for building any type of Carousel. Supports everything, accessibility, responsive, lazy loading and very easy to use