You're correct. Japanese isn't a phonetic language as such, it's syllables, with only the vowels and 'n' allowed to be alone, the rest are a consonant follow w

You're correct. Japanese isn't a phonetic language as such, it's syllables, with only the vowels and 'n' allowed to be alone, the rest are a consonant follow with a vowel (although the vowel is often omitted in speech), and there aren't very many of the. Therefore there are a zillion homonyms (and puns) and a lot of inherent ambiguity, which is addressed by context and, as you note, except for children, using full kanji (adopted Chinese ideographs). Publications for older children frequently use kanji with small kana to the right side called furigana for the kanji they're still learning. That said, as I understand it there are many fewer kanji that literate Japanese need to learn compare to the Chinese, about 1,800 by the time they graduate from high school. Japan also wasn't extremely isolationist until 4 decades into the Tokugawa Shogunate, so it's really a period of 1641 to 1853, and as Wikipedia puts it, correctly to my knowledge, it "maintained limited-scale trade and diplomatic relations with China, Korea, the Ryukyu Islands and the Netherlands".