Literally all studies of the Roman Empire start off by assuming that Latin was the langauge not only spoken and written by Roman elites but also by Roman peasants.
This ensures that normies don't question the origins of the Catholic Church, her subversion by (((Jesuits))) or the reason why many scientists such as Newton wrote in Latin.
The core of the reasoning for why it is not the spoken language is threefold and described below.

First of all most written sources come from authors that occupy elite positions in Roman society.
Examples of all famous authors being elites are Marc Aurelian(Roman Emperor), Seneca(advisor to the Emperor) and Livy(nobility).
This is aggravated by the fact that the original works of these authors don't exist(e.g. Meditations by MA copied by Vatican in 14th AD) and only Medieval copies works written down by "monks" can be found.
Therefore we don't even know for sure whether these emperors spoke Latin themselves but that is beyond the scope of this post.

>The average Roman citizen did not have access to writing materials so that is why no works pertaining to the lower classes are preserved.
However the following two points refute this:

Since Christianity was the people's religion according to scientists(with army officers following Mithraism and more masonic crap) it sure is suspicious that there are no Biblical texts in Latin.
Even worse, there are no crosses or any signs related to Christianity to be found in the early periods of the Roman Empire although it is rumored to have been popular among the soldiers in particular.
It goes even further: we have no books written by Romans to teach their pupils Latin whereas native speakers of most languages still study their language until a later date.