What kind of Latin are we learning in this course?
Are we learning Classical Latin or Vulgar Latin? Which is more useful to know?
Classical Latin. Vulgar Latin was the everyday Latin spoken by the man/woman in the street and varied from place to place, hence the different Romance languages. Vulgar Latin doesn't generally get taught and there isn't really any literature in vulgar Latin apart from the Vulgate Bible. And you can read that without much difficulty if you learn Classical Latin.
Vulgate Bible =/= Vulgar Latin. Vulgar Latin is a whole thing on its own. NativLang has a playlist on Vulgar Latin and its relation to Romance languages --> https://www.youtube.com/watch?v=C6gEDVV1YYc&list=PL6D46FA0337CE3F3D
Tl;dr: it’s impossible to truly learn “vulgar Latin,” only specialists can put it back together albeit incompletely. But, Classical Latin is valuable to help you understand the Romance languages.
Most of Vulgar Latin is reconstructed based on comparing the current Romance languages, studying the corpus of texts from the time in which the modern languages were definitely emerging (The Song of El Cid or the Oaths of Strasbourg), things like Roman graffiti, and a document called the Appendix Probi which was written by a monk who was complaining about various “errors” amongst others.
The two weren’t so distinct as to be unintelligible. However, if you spoke in the classical register people would have thought of you as strange. They’d have understood you but depending on when and where you were you would have been seen as anything from a very stuck up person to someone speaking with archaisms and a funny accent.
Of course we can’t speak of only one unified language either. Latin was a language spoken in one city that spread across Europe, North Africa, and the Middle East, often by point of the sword. It existed over a thousand year period. Speakers could have been people who only a generation prior had spoken a Celtic or Semitic language to colonists from Italy moving to some isolated islands.
In my opinion studying the classical language is valuable however. Most students in the US do it to boost their vocabularies. Beyond that it can definitely help you with the Romance languages, especially if you want to learn more than one. Knowing Latin will give you an idea of the patterns of the sound changes and while the grammar has radically altered it can help you to understand why certain irregularities exist within the Romance languages.