The alphabet is split by vowels in groups that are alike. The vowel, labial and linguals. The made by voice, by lips, by tongue (velar or coronal for even k is (tongue))
There’s myth that Fates in Pharaonida IO created vowels and B T
And the exception in the third row is of M. It doesn’t stand where labials are meant to be. The reasons why it’s so you can see at