@Lauren3193 Well, it's usually not really possible to tell if an actual Airbnb listing is "legit" or not. Very few wouldn't be.
Most of the questions about legitimacy here refer to scam ads that guests found on other sites which claim that they will use Airbnb for the booking. But aside from all the false claims in the communications from those scammers, the URLs for the listings aren't Airbnb URLs.
If you got a timely, friendly reply from the host that didn't send up any red flags, that's normally a sign that all is fine. If your check-in date is a ways away, and you don't get more communication from the host in the interim, it's a good idea to check back in with the host a week before check-in just to make sure all is good for your arrival.
Is there anything specific that caused you worry? Or just that it's new?
If no one ever took a chance on a new host or new guest who had no reviews yet, the platform would never have existed in the first place 🙂
Hope you have a great stay.