The epic of Beowulf exists as one of the oldest texts from the Anglo-Saxon period. Since the written word was not universal at this time period, epics (both poetry and prose) were passed down by word of mouth. Scops were the names of those who sang the tales used to entertain, educate, and carry on the history of the period.
Certain places exist within the modern translations which remind readers of the text's oral tradition. Given that the text was passed down for many years, prior to it being written down, the text surely changed numerous (uncountable) times. The use of the personal pronoun "I" reminds readers of the oral tradition of Beowulf.
As an example, take chapter one. The narrator (third person omniscient), who remains hidden for the majority of the text, reminds us of his or her presence: "I heard that orders to craft the gathering place were widely sent to many tribes throughout the earth." By using "I," the narrator reminds readers that the text was passed down orally (especially when combined with the remainder of the sentence--"heard that.."). This allows readers to readily recognize the oral nature of the text.