None of that was essential to know, but it makes Faine a deeper character. Knowing that, I can give a certain tone in Faine's dialogue that reflects how he feels about his past.
You can also create backstory to a town. In Aundes Aura there is a village called Tierra, and it sits at the base of the mountains. This village is situated next to the border of Meira, and used to trade with towns from the other country. However, the Church of Duthonne does not agree with the beliefs of the people in Meira, and thus contend that it is a sin to make trades with the country. The Church ordered the village to stop, but it did not as the trades were the most efficient way of keeping the village in stock. As a result the Church ordered a demolition on the village, and it was destroyed.
In knowing that, when the characters travel to Tierra they will discover what happened, and they notice how the village looks half-built as its people try to restore it.
So while backstory may not be essential to the plot, it helps immensely with creating a deeper world and deeper characters.
Character Development: This is the way your characters progress as people throughout the story. Character development is usually given between main plot points. It contributes heavily to pacing, as it breaks up the action of the story and lets us see how the character is adapting to his situation. Character development can be shown through either dialogue or, if it is the POV character, interior monologue.
World Building: How much world building you do will obviously depend on your genre. It is most prominent in fantasy and science-fiction. Deciding on whether you should show a particular feature of the world will depend on how unique it is from what we would find in our own world. For example, we all know what a dog looks like, however, it might be worth mentioning that in this world dogs have three heads and fiery tails.
Recently I had to make a decision on whether or not to show a scene in the church. I decided it was worth showing, as it is different to what you would find here. In particular, at the far end of the church there are gigantic statues of the four Great Gods. Elcalades the Giving stands in the centre of the other three statues, who face him. When someone needs to pray to a particular god, they kneel in front of the statue of the god they wish to communicate to and pray.
If the scene you have written does not contribute to any of these elements, it may not add anything to the story and just be filler.
Make every scene count.
To keep, or not to keep: That is the question
Whether 'tis nobler in the mind to endure that which is pointless,
Or to seek out that which is not; and in so seeking,
Give enjoyment unto another.