Should you reheat left out gumbo?

I wouldn't eat it. It sat too long in the danger zone of 40˚F - 140˚F. CDC, USDA et al recommend that food be left out no more than 2 hours.

There are better ways to cool food. 1. break it up into small batches 2. put the pan containing the food into a cold water bath to quickly cool it. 3. if it's a small quantity, put it directly into the fridge or the freezer.