I was showing a Japanese friend the kanji I have learned so far on WaniKani but they took issue with one of them, correcting me that the kanji 才 does not mean ‘genius’ but ‘age’. I went back to Wanikani to double-check but there is no mention of age, only ‘genius’, which my friend mentioned is represented by another kanji 天才.
I’d be grateful for shedding light on my confusion.
Kids learn 才 for “years old” instead of the proper 歳 because it is simpler. It’s better to learn 才 as “genius” since you will get to 歳 relatively soon (Level 46)
He probably confused “kanji” with “word” or just didn’t understand that you were showing him the kanji page, not a vocab entry.
天才 is not a kanji, it’s a word, and 才 on its own (as a word) is not used to mean “genius”, but used as a suffix for “age” (instead of the more complex 歳).