They allow the narrative to have a melody created through rhyme and structuring.
Explanation:
Alliteration, caesura and kennings are figures of speech capable of developing a musical, rhythmic and harmonious effect in a text. The use of these figures was very influential in the epic poem Beowulf, especially in the most important points of the narrative, such as the moment of the fight between Beowulf and the monster Grendel. This influence is due to the fact of the musicality created by these figures of language, through the rhyme and the structure that they create. This meant that the poem could be easily sung, in addition to being recited, since they had an applicable rhythm for songs.
The poet states that the statue had been destroyed and what were left was its leg and head. But in contrast to that the picture has a full statue with the entire body. Also the poet has stated that the face has a permanent frown due to ordering always, but here it does not seem to be. So therefore that is the one detail not clearly shown by the poet.