Is there any particular reason to why the Queen needs to be "Saved"?

If you’ve ever heard the British nation anthem or are acquainted with any of their past colonial states, you should have noticed that the words are “God Save the Queen/King”. My question is what the author/writer of the hymn had in mind when he wrote it. Did he perceive it that the Queen was in some sort of danger; even facing the horror of being killed? I think the whole piece is odd, since it praises the Queen first, and then in the punch line, pleads God to save her. From what? Shouldn’t it be more convenient to put the words “God Bless the Queen”, as the Americans use “God Bless America”?