If we want to get technical no one invented anything since pretty much every invention has been derived off of another at some point in time. Ignoring that....
Did Apple invent anything? Yes.
They brought a home computer with a GUI interface to the masses.
They created a fantastic, easy to use music player (ever use pre-iPod mp3 players? I did. Not pretty).
They created the iMac, the Mac Pro, Macbook Air, Macbook Pro, and Macbook. Are they computers? Yes, but Apple created them.
They created Mac OS, the iPhone (ever use a pre-iPhone smartphone? Garbage, all of them (which was mostly Blackberries).
They created the "usable" tablet industry in the form factor you see the iPad in.
They created a working system of digital content delivery. Like or hate iTunes, it was revolutionary and ended DRM on music.
Why people constantly try and downplay Apple's achievements is beyond me. Its a very revolutionary company who continues to make revolutionary products. If you don't like them, don't buy them.