In conclusion, long working hours are necessary for human beings.
I’m guessing this may be a cultural issue.
Let’s try a quick test. Which of the following sentences is NOT about working hours and humans?
Hopefully you chose number 3. In any discussion of working hours, and indeed of many other topics, we’re usually talking about human beings, unless otherwise specified.
The only time we really need to mention humans is when we’re contrasting them with non-humans!