I think if TikTok started as an American company and didn't have access to the FB-free Chinese market then it would have been crushed by Facebook in the American market before it could grow.
Tiktok does not have access to the FB-free Chinese market.
Yes it does. TikTok is known as Douyin in China. The company that owns TikTok is headquartered in Beijing, and Douyin was operating in China for years before TikTok was released in the west.
I'm aware of Douyin. However, TikTok and Douyin are different apps with different users. The product named TikTok did not establish itself in China first.