Menschen would sound weird because it has this emphasis on human, which is totally superfluous. On the other hand, if you talk about people suffering from a disease it makes sense to bring the human side in there.
An earlier question (see here) asked for the difference between Menschen and Leute. I would like to understand how "Volk" relates to these (like in the Reichstag inscription, see picture below). Is...
Leute / Personen / Menschen? Which one to use? Ask Question Asked 1 year, 2 months ago Modified 1 year, 2 months ago
vocabulary - Leute / Personen / Menschen? Which one to use? - German ...
Thus, "für die Menschen" is often used by politicians postulating what they think is important for the community as a whole, like "die Menschen brauchen mehr Grün in den Städten", and so on. This doesn't go for all imaginable cases, but I think it's a guideline for telling when to use the plural or the singular of "der Mensch".
preposition - Correct usage: "für die Menschen" or "für den Menschen ...
While reading some recent newspaper stories as well as book jacket introductions, I noticed that when describing the characters of the story the writers were often using "Personen" and "Menschen"
I actually would make a difference between "Die Menschen" and "Die Leute". "Die Leute" makes me think of a specific (e.g. the German) society. "Die Leute" is also connected to a certain degree with "the public". "Die Menschen" is more general and has more a taste of "the mankind". The difference to "man" is imho that "man" includes yourself: "Man sollte nicht so pessimistisch sein" can also ...