The iPhone's interface might be details, but the iPhone itself certainly wasn't. It singlehandedly brought smartphones (and the screen-only form factor) to dominance. Of course you can argue it was timing and someone was bound to do it, but others didn't do it.

The iPad "created" (again, technically just brought to prominence) the tablet form factor. The iPod fundamentally changed music forever, the shitty Apple earbuds are iconic in and of themselves, and barely anyone even purchases those.

Furthermore, I contend that Apple changed design as a whole forever. It takes high end boutique design and without fail sets a new bar across every industry they set foot in. Great design has become a prerequisite for consumer products. On the one hand this trivializes design in that few of the people demanding Apple-tier design understand the amount of work it takes, but on the other hand it means companies can look at Apple's astronomical margins and perhaps justify stronger investment in design.

The entire history of Apple is pretty fascinating, but from a design perspective alone (i.e. not necessarily a technical perspective) I think the last 15 years or so contain the highest density of notable strides forward.