What are the principles and values that characterize the Roman Republic?

One way to approach Roman principles and values is through the Republic's emblem, SPQR, Senatus Populusque Romanus, the Senate and People of Rome. The underlying principle was that the people had responsibility for their government; this was the Republic concept. Romans adhered to the principle that all authority came from the people. The people included the cives group, the citizens, who could include women. Only men could vote, however, and not every man was a citizen. The peregrini resided within the Republic, but they were not citizens. Finally, there were slaves, who had no legal personhood. Thus, one contradictory value in Rome was that some of the people could own others as property.Social governance embodied separation of powers. Two consuls were the top level rulers The Senate was a governing organization that represented one part of the people, the patricians or upper class; they were clearly divided from the masses, or plebeians, represented by the tribunes. The social values were codified in laws, passed by the Senate passed the laws, and their written form was recorded in the Twelve Tables.In addition to popular representation, other values were service, duty, and bravery. Rome expanded its rule through military expansion. In this regard, slaves often entered that status as war captives. They might be acknowledged by the Romans as embodying honor within their own native land. Over time, in recognition of their incorporation into the Republic, some slaves were allowed to become citizens. Over time, as well, the Republic underwent numerous changes, from its origin about 500 B.C.E. until 27 B.C.E., when the Republic became the Empire.
https://books.google.com/books/about/SPQR_A_History_of_Ancient_Rome.html?id=yKL4CQAAQBAJ&printsec=frontcover&source=kp_read_button

https://www.ushistory.org/civ/6a.asp