First off, thanks everybody for helping out :)
I misheard 人 as “ri” the first time but it is actually “nin” so I apologise.
Earlier in the season Koichi wrote that the kun reading is used to define quantities generally which is why I was confused about whether it was “shichi” or “nana”. I know there are no concrete rules about on’yomi and kun’yomi readings so I’ll go with the flow.
Thanks again everybody!