@szbalint I'm not convinced the Romans had the letter G. They would've rendered the name Gaius as CAIVS, because they didn't distinguish between the voiced (G) and unvoiced (C) consonant.
Another fun fact: V probably would've sounded similar in Classical Latin to our W, which is kind of similar to a U (think "ooh"), explaining why they got away with spellings like IESVS for Jesus. U only became necessary after V had become a voiced labiodental fricative.