Limelight App is a program that lets you add photos and files from your phone to create a slideshow. This app seems to have been designed with church functions in mind, although it can be used for anything if you add your own content.
The interface of Limelight App is not too difficult to figure out. There is no tutorial or other user guidance, but by poking around a bit you can get a sense of all of the features. You can add photos by tapping an icon in the upper left-hand corner of the screen, and you can browse through files or add them in the All Files tab. The app comes preloaded with the Bible and Amazing Grace, but you can add any other files and photos you want. Across the bottom of the screen, you'll see a miniature preview of the presentation you're putting together. You can't add text to images in the app, so you'll have to do that ahead of time, and then save it to your phone if you want to include it in the presentation.
There is also a More tab, but it doesn't bring up anything. And the TV or monitor icon at the top of the screen, which presumably is supposed to switch to presentation mode, doesn't seem to do anything, either. This app is free, so you might want to play around with it to see if it will work for what you need.