But English needs a mix of consonants and vowels, so the way you can combine characters is far more restrictive. bcd isn’t a word. jrl isn’t. You have to mix consonants and vowels. Also, the vast majority of words are three or more characters long.
Japanese, on the other hand, can combine literally any character with any other character. Pretty much the only exception is that a word can’t start with a singular “n”. Also, in contrast to English, any singular phoneme can have meaning. There is no lower limit to the amount of characters you need to actually make a word, again, with the exception of “n”.
So, even though Japanese has less phonemes, the syllabary is structured in a way that should allow for little to no homonyms, due to the flexibility of arranging characters. Instead, the opposite is true, and Japanese seems to have far more homonyms than any other language I’ve encountered.