How ancient are you talking? Chinese history spans a long history, many groups have come and gone.

In all seriousness, first you must realize that there is not one "Chinese People" within China there are hundreds of different ethic groups all living in various regions, mostly throughout history completely separated from each other. That said as typical in most ancient societies, ancient "Chinese" folk religions were often shamanistic. town would have a shaman who would predict the weather or of upcoming events. They would usually worship various gods through which they interpreted the world around them; as well as ancestor worship.
You still see elements of the ancient folk religions in various regions of China today, as most eastern 'religions' do not require a monopoly on your belief, people may follow a variety of practices and beliefs without any conflict.