Taste in music is subjective. Ed Sheeran is an amazing young talent and his cover of Stand By Me is remarkable. John Lennon was also an amazing young talent when he covered the same song, however his version was made more poignant by the back story of his love affair with Yoko Ono.
Ed Sheeran has his own version of Stand by Me, and so did John Lennon. John Lennon is a legend in his own right, and no one could ever eclipse him. To say that someone has blown him away, that isn't going to happen, anymore then someone can blow away the work of Elvis or Michael Jackson, these are legends they made their mark and its stands no matter what other artist may do with their works.
John Lennon was one of the most complex and influential musical artists of all time. He recorded a cover of Stand By Me as part of his Rock N Roll album while he was separated from his wife. His recording has a wistful and pained quality to it. Ed Sheeran has nothing on John Lennon.
Although Ed Sheeran's cover of Stand By Me is a great piece of work, it by no means "blows" away John Lennon's. Both are great quality versions of the song and both can stand alone and be great pieces of art. Each have their own unique style which allows it to flourish as an individual song piece.