If it wasn't bio lab created, then how did it spread so rapidly in China?
It didn't spread so rapidly.
Timeline of the 2019–20 coronavirus outbreak in December 2019 – January 2020WUFLU
1 December 2019
The first known patient started experiencing symptoms on 1 December 2019. He had not been to the Huanan Seafood Wholesale Market of Wuhan. No epidemiological link could be found between this case and later cases.[8][9][10]
8–18 December 2019
Between 8 and 18 December 2019, seven cases later diagnosed with Wuhan coronavirus were documented, two of them were linked with the Huanan Seafood Wholesale Market, five were not.[11]
12 December 2019
Chinese state broadcaster CCTV reported in a broadcast airing on 12 January 2020 that a "new viral outbreak was first detected in the city of Wuhan, China, on 12 December 2019."[12]
21 December 2019
Chinese epidemiologists with the Chinese Center for Disease Control (CDC) published an article on 1 January 2020 stating that the first cluster of patients with "pneumonia of an unknown cause" had been identified on 21 December 2019.[13]
24 December 2019
First publicly reported collection of virus sample from patient for genetic sequencing.[14][15][16]
Singapore's Ministry of Health (MOH) reported that the first case of what would later be named the 2019-nCoV (Wuhan coronavirus) had been diagnosed. It was later confirmed to not actually be related to the outbreak.[17]
25 December 2019
Report of medical staffs in two hospitals in Wuhan suspected to be infected and was being isolated around December 25.[18]
29 December 2019
According to a CDC publication on 31 January 2020, the facts leading up to the identification of the 2019-nCoV were as follows, "On 29 December 2019, a hospital in Wuhan admitted four individuals with pneumonia and recognized that all four had worked in the Huanan Seafood Wholesale Market, which sells live poultry, aquatic products, and several kinds of wild animals to the public. The hospital reported this occurrence to the local center for disease control (CDC), which lead Wuhan CDC staff to initiate a field investigation with a retrospective search for pneumonia patients potentially linked to the market. The investigators found additional patients linked to the market, and on 30 December, health authorities from Hubei Province reported this cluster to China CDC. The following day, China CDC sent experts to Wuhan to support the investigation and control effort. Samples from these patients were obtained for laboratory analyses."[19]