For example, did an ancient roman have an Italian accent? Or a Germanic tribesman have a German accent?
Or are things like that nearly impossible to be sure of since there are no audio records.
It's unlikely, as they were speaking very different languages than modern speakers.
If accents didn't shift overtime, then French, Spanish, Italian, and Romanian speakers would all have a "Latin" accent; all of those languages derived from Roman Latin.
Modern German, English, Danish, Swedish and Norwegian all derived from Old Germanic languages. While we can hear that there are similar sounds and words between these languages, the farther back they diverged, the more different they will sound today.
There would have been regional accents as well, which would, in time, develop into creoles and pidgin tongues as those regions were invaded by people who spoke with different accents or different languages altogether. With more time and regional isolation, accents can essentially develop into new languages.