Hey Jackie, great question. You are right in saying that there has previously been a man in the Captain Marvel role. In fact, there have been 6 people who have used that name since the late 60s. The name of Captain Marvel has become a legacy since the original Captain Marvel died of cancer back in the early 80s, with different people taking on the name at different times. Carol Danvers, the current Captain Marvel, is the latest to take the name after previously being known as Ms Marvel for a long time.