I know it's not an Apple innovation, but the innovation which has helped the profile of Apple the most is undoubtedly Windows 😛 .
I know everyone is going to say iPod, but I'd actually argue it was the original iMac in 1998. Even in my youthful naivety, it caught my eye. Completely changed my opinion of Apple. Before I saw the iMac adverts (I still remeber them vividly) I thought Apple was just another type of beige box computer.
The iMac redefined the Apple image. Without it, I don't think they'd ever have been capable of making the iPod (or at least incapable of popularising it).