Minestrone has a long long history that dates back hundreds and hundreds of years. Its popularity began wayyy back the 2nd century BC when Rome conquered Italy. Because there was suddenly a whole new culture living (and controlling) Italy, they brought some of their food with them from Rome. Suddenly Italians had a whole lot of new foods to try, and new vegetables were being planted. (Still no tomatoes! Those didn’t arrive from the New World until much later)
Instead of being limited to only a few vegetable crops, Italians could now enjoy a wide variety. It was this new mix of vegetables, and plates being made, that started the minestrone craze. Gathering ingredients from leftover meals, Italian peasants would make this “poor man’s soup”. That’s why even to this day, there’s no one exact recipe for how this soup should be made, and you are welcome to add, or leave out, anything you’d like to.