Plagiarism?

When I read Tolkien's letters it seems lots od people pointed out he had used many stories and taken out points for his stories But he made them his own with twists here and there.
When one submits one"s story, one of the first things the publishers and readers of said house want to know is which style you are in fact borrowing a little, say Agatha Christie or Tolkien or whatever. There is a saying that king Solomon wrote There is nothing new under the sun. So you just make your work totally your own despite there being similarities. You have a fine mind, you will do splendidly.