I am selling a bicycle that definitely won't be stolen. It's in working condition. If you service, clean, and lubricate it, it will last another 100 years. I ride it to Lidl a couple of times a week. Selling due to moving.
Never pay down a deposit in a bank account until you have met the seller, seen signed a purchase agreement.
No serious private advertisers ask for a down payment before you meet.
Receiving an email with an in-scanned ID does not mean that you have identified the sender. You do this on the spot, when you sign a purchase agreement.