Biased as I have one (grown up now)!
i chose it because biblical, means dove in Hebrew, liked the Play School and Beatrix Potter connection, also Jemima Goldsmith (then Khan) and Jemima Shore detective as growed up examples. It's also one of the Cats in the ALW musical.
NNs Mima, Mimes, Jemz and she now uses MYMA as a professional stage name.