This image may be more clear
This image may be more clear, talking about flat white marks in center
Unfortunately the skin of the penis experiences so many different things and circumstances it would be difficult to actually say what is going on. It is obviously not a severe condition.
I think if you went to see a doctor or even a dermatologist they would likely give no clear cut answer as to what these are. I think they would ask if you are sexually active and whether there was any possibility of risk taking practices, such as penetrative sex with with no protection.
Other than that, often it is a case of waiting to see if the issue becomes more severe, then investigate what the cause is …