Visa Free Possibilites

Good evening!
I am Brazilian and my flight is EWR > PVG (New Jersey > Shanghai) where I arrived at 02:05 PM on February 18th.

So on February 24th at 04:30 PM I'm leaving PVG> EWR
Is it okay to be in Shanghai without a visa? I would like to visit the Great Wall of China, can I go there without a visa?
Thank you very much