Letters are signs for sounds. Letters are not pictures or representations (…) and tho’ our letters may be shown to be derived form picture writing, such derivation is is so much part of the dim and distant past as to concern us no longer. Gill, 1931.A little concern for the G’s pre-Latin origins, then, but not too much:
Signs for g-like sounds can be traced as far back as 200BC (Egyptian hieroglyphs), 13BC (Semitic alphabet). There was a Phonecian ‘gimmel’ (11BC), a Greek ‘gamma’ (9BC), an Aramaic ‘gamal’ (8BC), a Hebrew ‘gimel’ (3BC), and a Syriac ‘gomal’ (2BC)… but the symbol remained virtually the same.