Yes it's very normal to see images when your eyes are closed.
Our eyes are just the things that allow the images to come into our brain but our brain is what processes the images so we can actually see.
Without our brain being connected to our eyes we still would not be able to see.
The eyes are basically a lens that sends the images we see through our nerves and into our brain.
The other reason we can see images when our eyes are closed is because of a thing known as phosphenes.
The Phosphenes are a combination of mechanical, electrical or magnetic stimulation that, even though they are considered a phenomenon, are very real.
This allows us to see when we are asleep and when our eyes are closed.