It would seem a sign of our times that words which heretofore had succinct definitions now have arbitrary definitions. In former days, one would refer to a word whose meaning has been altered as having been corrupted linguistically.
While what Miss Watson did certainly evidence courage, there does not seem to be an act of solicitous valor involved, such as saving someone's life, sacrificing oneself for the good of others, and such acts that were the requisites of a person's being called a hero.
"That depends upon what the definition of is is" -President Bill Clinton.
As the previous post suggested, the definition of a "hero" might be where one determines if Jessica is one. If someone argues that a hero is someone who does something that no one else has done or few could do, then perhaps Jessica Watson might be considered one. When Sir Edmund Hillary climbed Mount Everest and when Lindbergh flew across the Atlantic, some considered their feats heroic and their status as heroes. In what Jessica Watson did and in the manner she did it, perhaps under these conditions one could consider her heroic. I think the standards for heroism would be critically important in assessing Watson's status as heroic. I am not sure in my own mind, I could consider her heroic for my standards of heroism are different. Yet, the criteria that one uses would be the ultimate determinant of whether or not Watson fits the conditions of being a hero.
I guess this depends a lot on what you think a hero is. To me, she is not a hero. This is because it is not as if she has done something that is some big boon to humankind or even to her country. She may be a hero to few people who want to be like her, but I do not think she is a hero in any larger sense of the word.
To me, heroes are people who do things that help the whole world, or at least a large number of people. Usually, this would be done at great risk (whether that be risk of losing their lives or risk of having people hate them, etc). There was certainly risk in what she did, but I do not see who it has really helped.