The acidity of your average alcoholic beverage, even before fermentation, is enough to deter most bacteria. When fermentation begins, oxygen is removed from the must by the yeast, and they produce alcohol to combat other microbes. This creates a very toxic environment for anything that's not yeast. There's millions of species of bacteria out there, but only about 200 that can survive in either an active ferment or an alcoholic beverage. Which might sound like a lot, but good luck finding them in the everyday world.
Keep in mind that people have been making alcohol for thousands of years, and sanitizers have only been around 100 or so. The vikings used to dip a ceremonial stick into their must asking the gods to bless the beverage (little did they know the stick was covered in yeast but probably also tons of other things). People fermented in clay pots left in the sun exposed to all the elements without an airlock. They stomped grapes in an elevated pit in their bare feet. People may be neurotic about sanitation these days, but if you create an environment favorable to yeast, they'll take care of themselves and anything else that's in there with them (for the most part).
A note should also be made that none of us really work in a sanitary environment. Sanitation is like pregnancy. You're either pregnant or you're not. And unless we're in some sort of lab with filtered air and hazmat suites, none of us is in a sterile, fully sanitized environment. It's about creating an acceptable level of other bacteria. So we do our best.
That's all not to say, don't sanitize. DO sanitize. I would bet that people back in the day tossed more batches than we do, since infections can usually be determined by smell. But you're more than likely fine. I find cat hairs in my must all the time since if you have a cat, you cannot escape them.