Might want to consider starting a disk cleanup. Right click on C Drive and click Disk Cleanup then when the window pops up in the lower left hand corner click on clean up system files. I know that windows updates can store a lot of files especially when installing build updates, look at the delivery optimization files section as well in this same menu. You don’t have to execute the cleanup but you can use it to discover what else is using up space. Furthermore, what size is your page file set to? You’ll find that by right clicking This PC while in the explorer window. Then scroll down or look all the way to the right depending on if your window is maximized or not and select Advanced System Settings. When the window pops up you will see a tab called Advanced then under performance click settings. You’ll then be able to see how much space your page file is taking up. Don’t delete it! I have 32 gigs of ram and I still use a 20 gig page file but I direct it to another drive. But it can also be set excessively large so it’s worth it just to know how big it is. Furthermore, system restore points can begin to take up a lot of space as well.
Did you install the OS yourself or was it preinstalled? If it was preinstalled you could also have a recovery partition eating up space as well.
Cheers!