Chaucer is well known for giving himself a role in his classic, and telling the tales that the pilgrims share and the conflicts that go on between them from the perspective of another pilgrim who is part of the band of travellers. Note how he uses the first person after his descriptions of each of the travellers:
And now I've told you truly and concisely
The rank, and dress, and number of us all,
And why we gathered in a company
The use of the first person in "I" and "we" clearly indicate that it is Chaucer who is narrating us this tale and thus it is Chaucer who depicts himself to be one of the pilgrims travelling as part of the band. Depicting himself in this manner of course gives us a witness account of all the amusing fights between the various characters as we see the reactions and squabbles that arise in between the telling of each tale.