I got my first 1 star rating from a fellow uber driver. His car was in the shop, requested a ride. I got the ping. we chatted about the business and laughed. dropped him off, got 1 star. obviously trying to gain a competitive advantage. Like you i was very upset and reported it to uber who did nothing and never will. What I can tell you is, that will disappear after a while. I have a 4.96 rating after 1647 rides. The average is 4.80 i believe. I have received 1 star ratings for no reason whatsoever. I stopped getting upset because there is nothing you can do about and uber doesn't care. You will recover and it will happen again, I can promise you that. I have received 1 star ratings for not letting pax bring an open container in my car, for not allowing more than 4 people in my car, for not allowing toddlers in my car without car seats. All of those are illegal but uber still won't take them off my ratings.
Oh, btw,,,, welcome to uber. You will be fine and your ratings will recover over time.