Adding depth to 2D image

So, I'm sure this topic is out there but I'm just not finding it.

I have a round 2D image (a PNG file) that I'm making rotate with some background animations.  Righit now, the image rotates  but has no depth.  I found a tutorial on YouTube but it's basically duplicating layers and after about 15 layers, it creates a square that rotates instead of just the round image.

Is there an easier way to just add some depth to this PNG so it doesn't look so flat?