This is a very good introduction. It's about the right length (c8%); gives a little relevant background and context, indicating that the writer has thought about what a stereotype is in its broadest interpretation; makes some initial references to sources; and finally focuses precisely on the question, showing the reader that it has been fully understood and that it will be answered. Note that the wording of the final part of the introduction is very close to that of the question. If the essay follows in the same vein, it should get an excellent mark.
Overarching Societal Statements: Rather than using a traditional thesis statement you can put forth a societal observation that ties into the theme of your essay. This can be very effective if the statement is unique and gives a glimpse into how you view the world. It can be detrimental if your statement is debatable or unclear. Make sure that if you use this form of introduction that no admissions office will take offense to it.