Yea everyone knows how they work, you aren't lifting the veil here. But as other comments point out, air fryers are actually very similar to ovens. You seem to be confused that the word "fryer" means that they need oil.
Oil is optional, just like in an oven. Would you call oven cooked chicken "fried" because it was basted in olive oil? The same chicken can be air-fried, basted or not.
Even then, basted chicken, and basted potato chips, use far less oil than an oil fryer. This has some health benefit, it's also way more convenient.
Apart from being clever marketing, I believe they use the word "fryer" to describe the immersion in a very evenly and highly heated fluid, in this case air.
While not very different from a fan-forced oven, the design of a small chamber with a vented basket and high air circulation does create a more uniform thermal environment over the entire surface area of the food, than the usual convection oven with a flat tray.
