Problem: What are the most important words?
shadows of the trees moves on the wall
Answer: move, shadow, tree

Problem: What are the most important words?
stained glass window depicting prophet offering a sacrificial lamb to deity
Answer: deity, offer, prophet, stain, window

Problem: What are the most important words?
an astronaut drifting in space is rescued by a space shuttle orbiting earth
Answer:
earth, orbit, rescue, shuttle, space