Answer:
I am so simple that I can only point. Yet I guide men all over the world.
Someone walked into a room and you heard a crash! Someone died. What happened?
You get many of me, but never enough. After the last one, your life soon will snuff. You may have one of me but one day a year, When the last one is gone, your life disappears.
Three little letters, a paradox to some. The worse that it is, the better it becomes.
One by one we fall from heaven down into the depths of past, And our world is ever upturned so that yet some time we’ll last.
Black we are and much admired. Many seek us if they are tired. We tire the horse, and comfort man, and turn White when we've fulfilled your plan.