In my experience, it can be very difficult to tell the difference between a false negative and a real one when it comes to consumer products...especially if you focus on finding the reasons for the negative outcome.
Instead, I think the best advice is to put your engineering 'solve the problem' hat aside for a moment, and instead put on your marketing 'follow the enthusiasm' hat.
Try to figure out why the people who did buy in were excited about your idea. There are probably only a few reasons they got excited, and if you are lucky and honest with yourself, one or two of those reasons will point towards a the business opportunity.
Learn what those people have in common with each other, and then tweak/pivot to make them even more enthusiastic. Maybe they are all moms with kids who want to be frugal and fun but never buy cookies anymore, so you should get Oreos to include it in a promotion to attract those ladies and their kids back into the Oreo family... Who knows.
But don't try to figure out why more people didn't buy in - there are gazillions of reasons, and thus gazillions of possible actions each with their own unknown outcomes.
This first stage of product development is unpredictable, so spending a few months to learn what you've learned seems like par for the course except for a very few very, very lucky perhaps mythical entrepreneurs who get it just right at the start. If you were hoping for a home run and instead got walked, you need to decide how you feel about that situation now that it happened. Is running the bases fun for you, or would you rather play a different game?