Latin and the Romance languages are indeed very different, but their similarities are much stronger than just vocabulary. The Romance languages have lost noun c

Latin and the Romance languages are indeed very different, but their similarities are much stronger than just vocabulary. The Romance languages have lost noun cases and gained prepositions, fixed word order, and definite articles, but they retain noun genders (though without neuter), remnants of the case system in pronouns ("je", "me", "moi"), many of the same verb tenses, and the subjunctive/indicative moods, to give a few examples. Anyway, my point is that it's an error to say that Latin "stopped changing". Other languages have changed similar amounts: modern Americans can't understand Beowulf, modern Greeks can't understand Homer, and modern Chinese people can't understand Confucious, but nobody would claim that English or Greek or Chinese died and stopped changing. The fact that people call Latin, but not English, a "dead language" is purely due to the fact that the different stages of English all happen to be called "English". In an alternate world where Latin was exactly the same as it was in the past, and Italian is exactly the same as it is now, but Latin had never spread outside of Italy, I suspect that we would today call Latin "Old Italian" (or perhaps we would call Italian "Modern Latin"), and nobody would be having this discussion, despite the scientific/linguistic facts being identical to what they are in our reality.