Invention on its own is worthless, you should know that as a compiler writer. All the blood, sweat and tears to make an invention practical, that's the real innovative work. Ideas are cheaper than execution ("ideas are a dime a dozen").
Getting back on track, Morse code can be used with tap codes, with mirror/lights and other equivalent systems, it can be used in writing, it can be used in many, many practical ways.
Morse code could have been applicable since thousands of years ago. The fact that it wasn't invented earlier and adopted for practical things (of which there were many, and of super high impact!), proves that it wasn't as obvious an invention as you say. The Chinese had mirrors 4000 years ago (!), coupled with a code such as the Morse could they could have caused a battlefield (and also country management) revolution.
In a similar vein, many pseudo-writing systems (your prisoners tapping) have been invented across the centuries. However, throughout history there have been only a handful of full-blown real writing systems invented, and most of our writing systems actually derive from those. An entire continent basically didn't have writing because of how hard it was to come up with that "simple" concept, only 500 years ago.
Some good observations, allow me to deconstruct them :-)
I did mention literacy as a prerequisite. I'll add another one - an alphabet. Both those are non-obvious, and took a looooong time to invent. (The Chinese writing system probably prevented them from inventing the printing press with movable type, simply because trying to cast several thousand letters was out of the question.)
I'll add have you ever tried signalling with a mirror? I have (as a boy). It's really hard. The big problem is you don't know if the beam actually crossed the recipient's eye. About the best one could do is he sees a random flash now and then, not an organized system of timing sensitive flashes. Navy ships use signaling lamps, which solve that problem nicely, and they use Morse with it.
Signaling towers were used in Europe before Morse, where different positions of levers were used for different letters. This system worked, but it was slow and very expensive, and didn't work at night.
Morse actually came up with Morse code first, then tried to invent an electric telegraph system. His predecessors had come up with other various encoding schemes, but they were all impractical because they were too complicated for the primitive electric technology of the time.
The point is, people had no trouble coming up with encoding schemes for the alphabet.
Anyhow, see "The Victorian Internet" by Standage for an entertaining history of the topic.
Invention on its own is worthless, you should know that as a compiler writer. All the blood, sweat and tears to make an invention practical, that's the real innovative work. Ideas are cheaper than execution ("ideas are a dime a dozen").
Getting back on track, Morse code can be used with tap codes, with mirror/lights and other equivalent systems, it can be used in writing, it can be used in many, many practical ways.
Morse code could have been applicable since thousands of years ago. The fact that it wasn't invented earlier and adopted for practical things (of which there were many, and of super high impact!), proves that it wasn't as obvious an invention as you say. The Chinese had mirrors 4000 years ago (!), coupled with a code such as the Morse could they could have caused a battlefield (and also country management) revolution.
In a similar vein, many pseudo-writing systems (your prisoners tapping) have been invented across the centuries. However, throughout history there have been only a handful of full-blown real writing systems invented, and most of our writing systems actually derive from those. An entire continent basically didn't have writing because of how hard it was to come up with that "simple" concept, only 500 years ago.
Your comment strikes me a lot like being straight out of this famous story: https://en.wikipedia.org/wiki/Egg_of_Columbus :-)