Greetings, fellow humans. I also am a normal human, like you. Definitely not an alien learning your languages to one day overthrow your species.
Are you going to sneak into the white house disguised as a banana?
Why isnt it "hello, humans!" Doesnt mensen mean humans?
Yes, but it also means "people" and is more commonly used that way.
Is this a natural, common thing to say (like "Hi, folks!"), or is it a Duolingo-special type sentence?
Yeah, it's pretty normal. "Hi, folks" is a good translation, actually.
Thanks! Where does it fall on the formality scale from "Hi, folks" to "Greetings, ladies and gentlemen"?
"Hi folks" or "hi people", is a popular phrase, you could use it for friends or young people for example. Your "greetings ladies and gentlemen" is much more formal for people you don't know or are older than you. It would be more polite in this case
Thanks, but that distinction was presupposed in my question, which was designed to understand the register of the Dutch expression.