Knowing that much of the readership here is from the USA, that about half the adult population of the USA seems to believe in creationism, and that everybody has to profess a belief in God, nevertheless I want to point out that the piano did not suddenly pop into existence fully formed some 300 years ago as if from the hand of God.
No. The piano has evolved, and is still evolving. Just seven years ago the world's first 108 key concert grand piano was built in Tumut, Australia, about 100-km from where I live in Canberra, by the Stuart and Sons mentioned above. The lowest note is 16-Hz and the range is almost two octaves more than the 88-note pianos that ruled the last century. They in turn had about twice the octave span of the first recognised pianos by Cristofori.
Christofori did not start from scratch, either. He started from the harpsicord, which was itself a development of the harp. The harpsicord adds a keyboard, where pressing a key causes the corresponding string to be mechanically plucked. Unfortunately the player cannot control the volume of the plucking - Sir Thomas Beecham described the harpsicord as sounding like "two skeletons copulating on a tin roof".
Christofori's mechanism converted the 'pluck' into a 'whack' where the player could control the volume depending on the speed the keys were pressed, emphasised by the words forte for loud and piano for soft. Mozart had to make do with about five octaves. It took about 100 years for iron frames to find their ways into pianos, allowing much more tension to be applied to the strings. The fortepiano evolved into the pianoforte.
Beethoven in particular forced much of the evolution, getting up to 6 ½ octaves in his last compositions and trying to use the German hammerklavier rather than piano to describe the instrument.
Although the number of keys seemed to have stalled for a bit more than a century, overall sizes, orientations and capabilities did not. I am especially thinking of recording pianos which punched, and could replay, piano rolls. 2L has released a superb surround recording of Grieg’s Piano Concerto which is the equal of any modern recording, though the piano part was recorded over 100 years ago by Australian pianist / composer (and sad-masochist) Percy Grainger.
Metallurgy did not stand still either. Modern steel wires have far higher breaking strengths these days. Even cast iron has been transformed from an extremely brittle material into a ductile one that can be used, for example, for engine crankshafts. Moulten iron from a blast furnace is supersaturated in carbon, and when it cools the carbon precipitates as graphite sheets which give grey cast iron its colour and its weakness. Adding a little magnesium makes the graphite form into balls which are more benign!
Stuart and Sons have done more than extend the keyboard. They have revolutionised the way the wires feed the frame, downwards rather than sideways. They have optimised the cast iron frame using Finite Element Analysis, and even added a fourth pedal which moves the hammer pivot closer in, allowing more nuanced softer passages.
Not to mention electronic pianos ...