The sound of ZH

What if we invented an alphabet? How to proceed?
I would ask someone to talk, a sentence at a time. Then I would halt, sentence by sentence, and invent symbols for the sounds within each word of the sentence. After not very long, this process would probably derive an alphabet suitable for representing most words in English.

But we would not come up with a character for soft-z-soft-j, the sound of 'zh', because this sound does not occur in an English word. As children, we all made this sound by pursing our lips, pressing the sides of our tongue against the inside sides of our lower teeth, keeping the tip away from the front teeth, and blowing softly. It was one of the motor sounds for cars in the sandbox.

But it is a sadly unused sound in English. Which came first, the language or the alphabet? If language first, then there was indeed no need for a 'zh' character in the English alphabet. If alphabet first, then our creation of new words was influenced by the practical necessity to represent them with letters in our alphabet - so, the 'zh' sound was avoided, or perhaps even experimented with but discarded.

All of this seems very odd, given our extensive experience with this sound as children.

Russians have a special character for this sound, as well as some others. The French simply use 'j' for 'zh' ('Jamais!') and avoid the hard 'j' familiar to us English speakers. But, not in English do we speak this sound, at all.

What if we indeed had 'zh' thoughts and needed to express them? But not the alphabet to carry it through? Then our 'zh' thoughts would remain bottled up, rattling around within our souls, unexpressed. How tragic…