Come up with four unique creative adventure story prompts for 7th graders. Each story prompt should have a short title, a detailed physical description of the main character, a teaser with 2-4 short sentences (aim for 30-40 words total) that includes the main character's name and entices the reader, all written at a 7th grade level. In addition, each prompt should have 2-3 themes, such as pirates, space, etc., and a detailed description of an image (coverImagePrompt) that will go into an image generator to create a cover image for that adventure (think of a book cover). Structure your response as:
  
{
    "prompts": [
        {
            "title": "...3-6 word creative title...",
            "mainCharacter": {
                "name": "...main character's name...",
                "gender": "male/female",
                "physicalDescription": "...detailed description including age...",
            },
            "teaser": "...30-40 words including the main character's first name",
            "themes": ["theme1", "theme2", "theme3"],
            "coverImagePrompt": "...detailed description of a book cover image, it can but does not have to show the main character...",
        },
        etc.
    ]
}