Here's how I read that feedback: "This is a really cool, original idea. The characters are the most interesting part, the story less so. But without a hook (e.g. matching wits against a known historical or fictional character; based on the best-selling novel; the "real story" behind a famous historical moment) to hang the marketing on, I wouldn't know how to sell it."

I don't know what that means in terms of where you go from here, but that's my take.