Why was nicolaus copernicus’s theory that the earth orbits around the sun so shocking to people that lived in the 1500s?

Due to the lack of technology that they didn't have that we have today, they didn't believe Copernicus' theory. During the 1500s, you would know nothing about the orbit and how a planet moves, they would see that only the sun is moving. Since they only see the sun moving, they think that earth is stationary and the sun is moving around it, since when you look at the sunset you would see the son physically moving.

2018 means 2018 ce or common era

there have been other eras too including bce, which included way more years.