Hey there looked at your blend file. Here are some tips you can use to improve your animation.
- bring your background closer to the camera.
- instead of principled bsdf use emmision shader for the texture of the background.
- in the screen material of your phone just plug in your pic directly to the color input of the emmision shader and delete the rest.
I myself am a beginner in blender so I hope these tips help. Also checkout my own mobile commercial which I recently posted.
Mobile commercial