During the medieval period, middle English changed to modern English.
The people on the streets spoke their native languages (English, Italian, French...) but during most part of the medieval era the "culture language" and international one was Latin. Later French.
The monks in monasteries were instrumental in preserving and maintaining the English language during the medieval period, particularly after the Norman Conquest in 1066. Their dedication to transcribing and translating texts helped ensure the continuity and evolution of the English language.
During the medieval era in Europe, Latin was the language of philosophy. Other places used different languages.
The average person spoke a variant of what we now call "Elizabethan English". This was the language spoken by Shakespeare, added to by the greater commerce between France, Germany, and Spain (which changed our English greatly).
Yes, Angles were one of the Germanic tribes that settled in England during the early medieval period, along with the Saxons and Jutes. Their language and culture had a significant impact on the development of Old English, which served as the basis for the English language we know today.
The common language for medieval French was known as Old French. It evolved from Latin and was spoken from the 9th to the 14th century. Old French was the main language of literature and legal documents during that time period.
Before English, the official language during the period of resistance was Portuguese.
One of the most common languages being spoken during the medieval era was Latin. Another language that was being spoken during that time was French.
The Normans added words to the English language during their occupation.
Before the Norman Conquest, almost the only English words of Latin origin were Church-related words. These included "bishop" from Latin "episcopus".
The French was spoken only by the nobility, so the common people spoke English. For 300 years no King of England spoke English. Even today our words reflect this difference. The language of the court systems is French and the Queen's menu is still in French. It was easy to tell in Medieval England who was noble and who was common ( without taking into account clothing) by language.
The United States does not have an official language. English has been the language most spoken during our history.