Possibly. I've ordered "sterling silver" from the Wish app and they are sterling over copper. Just because it doesn't stick to a magnet doesn't mean that it's real.
Yes, just because it does not stick does not mean that it is sterling silver. Silver is normally mixed with Copper and there are several levels of purity that indicate the quantity of pure Silver contained in the metal. Jewelry is made like this all of the time. It's a very pretty piece though.