I understand about there being possibly many alternative readings for a kanji, and that WaniKani starts off with the most common. What I don’t quite get is a situation where two alternative readings are given. For example, for Person, ie 人 , two readings are given: にん and じん , and there are sort of two mnemonics about Nintendo and wearing jeans.
Are these common alternative readings, eg like some people pronounce “either” as EE-thə whereas others say EYE-thə and you can use whichever you prefer? How important is it to know both of them? I suppose if they are alternative pronunciations then you would need to know both as you might encounter either of them.
A related question is: do I need to remember whether a given reading is the on’yomi or kun’yomi? Most of the very early ones (I’m only on the first level) seem to be on’yomi, but maybe they are just the most common for these kanji. For example, I’ve just done 山 and the given reading is the on’yomi さん Do I need to remember that this is the on’yomi reading, or just remember what it is and maybe some others will come along later? I know virtually no Japanese at all but I do know that there is a kun’yomi reading of やま for this particular kanji, which I will presumably meet later - if I get that far!
Apologies if this has been asked and answered before and I’m just not doing well at finding it.
The biggest thing to remember is that the core of the language is the words themselves, not the kanji/reading relationship.
With じん and にん for 人, the use of one or the other is dependant on the individual word in question. Don’t think of them as interchangeable (though there are some cases where two words that are read differently can be written with identical kanji, but often there’s a meaning or nuance change.)
人工 is じんこう and not にんこう because of historical fluke to some extent (one reading is older than the other) but if you want to communicate that word, you have to say じんこう. If you said にんこう it would not register as an existing word for the listener.
As for on/kun, it’s probably not necessary to worry about it early on. As you progress, you’ll notice patterns.
The reading will be different depending on the word. They are not interchangeable (for the most part).
If I were to give an example based on English let’s look at numbers.
Let’s take number two. Similar to kanji we have a symbol that encodes the idea of two: 2.
But depending on the word the reading will be different:
2 - two
2nd - second
2le - double
About alternative readings
Some words have interchangeable alternative readings, for instance:
継母（ままはは、けいぼ）
山道（やまみち、さんどう）
but you shouldn’t worry about these as a beginner, they are not very common, and usually have a preferred reading that is enough for you to know.
I think more or less all the important stuff has been said, but I figured you might find this interesting:
Well, see, I think knowing possible readings for a kanji – or possible kanji for a reading, though that’s often much less practical – is only really important in one case: when you need to guess what word you’re looking at/hearing. However, I guess you could say this is generally a fringe application for your knowledge, and most of the time, it’s gonna be your prior knowledge of words that helps.
Still, if it’s any reassurance, here’s something I saw maybe… a week ago at most? (I’m living in Japan right now.) There’s a train line in West Japan called the 京阪線 (I’ll omit the reading for now). I was on a different line, and I heard two Japanese women talking about that line as we approached an interchange where you could head over to that line. One of them said, ‘Kyouhan…? Oh, keihansen.’ The reason for the hesitation: you can read 京 as either ‘kyou’ with a long O vowel (like in Kyōto=京都) or ‘kei’ with a long E vowel. Since we were around Kyoto, it probably made more sense to read it as ‘kyou’, but it’s actually pretty common to read it as ‘kei’ too when it’s in compounds.
As it turns out, the official reading of the train line’s name (京阪線) is ‘keihansen’, but this is ultimately something you have to just know by learning words and conventions (in this case, the preferred reading for 京 in this train line’s name). Point is, even Japanese people don’t know the right reading all the time the first time around. You can make good guesses, and that can help you communicate in a pinch, but everyone (native speakers included) will have to check some reference source at some point (could even just be another Japanese person’s speech) in order to be sure what reading to use.
Thank you - it was interesting, and also comforting that things can be tricky even for native speakers. I was actually in Kyoto a few months ago and that is basically how I’ve ended up trying to learn some Japanese. That was my first ever visit to Japan (and I’m retired) but hopefully not my last - maybe next time I’ll have learned enough to try something a bit more sophisticated than pointing!