I think the answer may involve the possibility that at the beginning of the poem, there simply wasn't a clear distinction between the poet and the speaker.

答案可能包括了,在诗歌的开头,根本就没有一个清晰的区分的可能性。

耶鲁公开课 - 弥尔顿课程节选

There wasn't an uncouth swain at the beginning.

开头并没有一个粗鄙的年轻人。

耶鲁公开课 - 弥尔顿课程节选