What is this peeling that appears on the skin, is it skin or cream residue, and does it prevent water from reaching the skin when performing ghusl from janabah?

Cream differs from ointment. Cream dissolves in a water-based solution and is almost entirely absorbed by the skin, leaving the skin dry after absorption. What you see is dry skin, not cream residue. Even if some cream remains, it is removed with a small amount of water and therefore does not invalidate ritual purity (tahara).