Pixel Animator is an app to draw and animate sprites using a very simple interface. You can decide if you want to create pixel art from scratch or prefer to upload a photo to work with.
In Pixel Animator, you can find the basic tools you'd expect from an app like this. Use the pencil to draw simple lines on the canvas, the eraser to correct imperfections, or the paint can to fill in spaces. Obviously you also have buttons to undo and redo any changes.
Once you're finished working with your drawing, just save the result to your device or share it on any social network. The file is saved as a GIF, so you can open it with any other app or program to continue editing it later.
Pixel Animator is a good app for making pixel art that, despite having a rather unattractive interface, is easy to use. Its main problem is that the app is somewhat unstable at times.