You could have something taking up a lot of space which doesn't immediately leap out at you. As an example, I listen to a lot of internet radio. To do so I simply click on a link in a web page. (i.e. I don't use a media player, such as Windows Media Player). However I found that I was running out of disk space and, when I investigated, it turned out that over half the disk was taken up by temporary files linked to Windows Media Player (even though I'd not knowingly been using it). So it's possible that you've also got loads of temporary files hogging loads of space.
Download, install and run the free version of CCleaner:
https://www.ccleaner.com/
(When you run it, just check that the 'Cleaner' section is selected in the left-hand panel and click the 'Run Cleaner' button. The default selections should be all you need to use).
That might free up quite a bit of space.
If that doesn't do the job, download, install and run WinDirStat, using this link:
https://www.fosshub.com/WinDirStat.html/windirstat1_1_2_setup.exe
That will allow you to explore exactly what it is that's taking up all the space.
If you really don't want all of the Windows 10 updates, the trick is to tell Windows that you're using a metered connection (i.e. one with a data cap). See here for the instructions:
https://www.howtogeek.com/226722/how-when-and-why-to-set-a-connection-as-metered-on-windows-10/
(Note that there are different instructions for wifi and Ethernet connections). You'll then only get the really important updates.