Thrips DO bite humans.
If you have ever been bitten by something but look down to find nothing there, you could have been bitten by a thrips. (Thrips is the singular and plural form). Measuring in at a minute 1/32"-1/8" long, thrips are difficult to immediately see.
Why Do Thrips Bite?
Thrips do bite humans but not as a defense mechanism as with many other insects. Thrips bite as a means to discover food sources. Though some thrips species will feed on other thrips, insect larvae, and mites, most are phytophages, feeding on plants and plant parts. So soon after a thrips bites you, it will discover that you are not a food source and move on.