i just dont know how dits scratched, i have been soooo careful
Well I think of your Pixel had been damaged in transit, you would have noticed right away. Unfortunately you probably picked up a normal level of wear and tear. You may think you've been babying your phone, but all of us, as we go through our days and our routines, put on a bit more wear and tear than we realize. Grit comes from so many sources. At the beach bits of sand get everywhere, even into phone cases--it drives me nuts because I vacation at the beach a lot.
In the city, grit comes from bits of concrete and brick dust from your environment getting kicked up a bit. I never realized how true this is until I visited a few big cities and could feel it on me at the end of the day.
I currently live out in the country and pick up grit from landscaping. It takes just a little bit of silica from all these varied sources of grit to scratch our phones and watches and eyeglasses and jewelry. Sometimes you just get unlucky and stick something in your pocket or carrying bag that sheds a bit of grit that does a lot of damage before you catch it. I actually periodically vacuum out the pockets of my work jeans and purses because this can happen and laundering my jeans does not help.
Have you had problems with scratches on previous phones? What did you own before?