Run the Apple Diagnostics.
Boot into Recovery Mode using Command + R and run Disk Utility First Aid on the drive to see if any repairs are needed.
I've seen a couple of our organization's laptops run into the issue where I was unable to open some downloaded .dmg and .zip files. The only solution was to erase the physical drive and to reinstall macOS or restore from a backup. These laptops came in to be repaired for other issues which I don't know if they issues could be related to the same defective part. I suspect some type of corruption occurred to the files due to an issue with the SSD, since after a clean install that particular problem never recurred.
I would suggest backing up your system if you don't have a recent good working backup. You should always have regular verified working backups. Boot into Recovery Mode (Command + R) and erase the physical drive as GUID partition and APFS (top option). You may need to click on "View" within Disk Utility and select "Show All Devices" before the physical drive appears in the left pane of Disk Utility. The physical drive should be identified something in the form of "Apple SSD ....". After properly erasing the drive you can reinstall macOS or restore from your Time Machine backup.