The Roman calendar started in January at least as far back as the second century BC, and my understanding is that our sources are inconsistent as to who changed

The Roman calendar started in January at least as far back as the second century BC, and my understanding is that our sources are inconsistent as to who changed it, when it was changed, and why it was changed. Also, most of our sources are writing well after the change occurred (generally, they date to first century AD). (This is why the Julian and Gregorian calendars start on January 1, because the calendar they're based on did as well! Although lots of European countries did decide for much of the past 2000 years to start the year on other days like December 25 or March 25 or Easter). This gives me a vibe that a lot of the tradition of the Roman calendar numbering is based on a "just-so" story that is made up to explain an interesting fact without being based on any actual evidence.