12 For who knows what is good for a person in life, during the few and meaningless days they pass through like a shadow? Who can tell them what will happen under the sun after they are gone?
This passage seems to be talking about mortality. Ever since the fall of mankind, our lives are numbered here on Earth.
What is the point of toiling? What is the point of being wise? What is the point of wealth and long life if everyone goes to the same end?
Fortunately for us, we have the hindsight of knowing that Jesus died for our sins, and that we do have somewhere to look forward to, when all comes to an end. At last, it is meaningless no more.