In China before there was a huge outbreak there is absolutely no way you can expect a small number of cases of a virus that nobody knows exists to be picked up. By the time of the big Wuhan outbreak there are already different variations in the virus. It had been in some population for a while before it broke out.
So the first outbreak in NYC is analogous to Wuhan. It could have started in Wuhan or it could have started anywhere else and then Wuhan had the right combination of factors for the outbreak to surge. We don’t know for sure.
>There are two subclusters of A which are distinguished by the synonymous mutation T29095C. In the T-allele subcluster, four Chinese individuals (from the southern coastal Chinese province of Guangdong)