For example, did people alive in 46BC call their current year 46BC? Or did they count their years from a different starting point?
Hello,
calendar-questions are very common and have their own section in the FAQ. Have you already checked it? https://www.reddit.com/r/AskHistorians/wiki/calendars
Short answer: No, people would not have known that they lived 46 years before the birth of our Saviour (BC), which they could not have predicted. They would have used a variety of local calendars, e.g. "during the 12th year of the reign of our good and wise ruler XYZ IV." or "during the year of consul XYZ". The current AD/BC calendar would not gain traction until a some centuries AD.