What I like about the code talkers is: the Japanese knew it was Navajo. But even that wasn't enough, because they used particular code words, so even if you knew Navago it didn't solve the problem.
Kind of like you may hear a language, and recognize what it is, but no idea what they are saying.
The Navajo language was not written at the time, and it’s very different than others and subtle differences in tone can make all the difference. Their written notes of what they heard were probably generally inaccurate which made breaking the code impossible (vs enigma which was exactly copied, and the output is German, they just then needed to break it)
But even that wouldn't have worked.
There were Cherokee, Choctaw and Lakota code talkers in World War I.
1. https://www.cia.gov/stories/story/navajo-code-talkers-and-th...