What do you think the temperature is in your refrigerator? Before electric fridges, people kept food for days in an ice box, which was typically in the 50s inside. Before that, they kept food all summer in a cellar, where temperatures are typically about 50 where they are insulated by a trap door from atmospheric temperature.
Enjoy your soup, and stop worrying about it. I’ve been eating leftovers for decades that I forget and leave on the stove overnight, at 70. Probably almost every week.