Piano is just 300 years old? There's more.

Yup, the piano is relatively young, but technology has pretty much maxed out it's capabilities.

Heck, valved horns are in much the same age bracket.

The Arpeggione, unfortunately, didn't age as well...

B

There is a fairly recent recording called “Fantasie” by Alexander Melnikov where he plays a number of different keyboard instruments—harpsichord, tangent piano, fortepiano, and modern pianos.  It is a very worthwhile recording to seek out.

Haydn wrote a gazillion baritone trios

There are quite a lot of aficionados for fortepianos.  Generalizations are always difficult.  Many fortepianists are excellent musicians but in general I dislike the instrument. It sounds like a pre pubescent harpsichord to me.  It’s easier for a sensitive pianist to scale down a Steinway to play Mozart than to have a fortepianist try to project Beethoven 

This timeline intrigued me. It struck me as illogical as it tells us that the earliest instruments were flutes.  My Grove Dictionary says there is a lot of controversy on this subject.  I always supposed some sort of rudimentary drum, but thinking it through now that can't be right either.  The answer is clear and can't be in doubt:  The first musical instrument had to be the voice.  Cheers and thanks for this stimulating post.