Don't want iCloud Drive to sync - is this possible
The purpose of iCloud is to sync, so the answer is no.
If it syncs with my iCloud Drive Folder and someone steals my Mac and deletes my hard-drive, all my synced files in the cloud will also disappear.
No. It's the other way around. If someone steals your Mac or your drive dies while you are using it your documents are still safe in iCloud for your other devices and your next Mac to access.
A protection against loss of data in the event of device loss or theft is Activation Lock. See Activation Lock for Mac: "With Activation Lock, your Apple ID password or device passcode is required before anyone can turn off Find My, erase your Mac or reactivate and use your Mac."
I want something like OneDrive, which allows users to copy files to the cloud for off-site storage/backup.
iCloud is like OneDrive in that you can upload files and sync them using iCloud Drive folder. iCloud does more than One Drive - you can upload all your photos and have them available to all your other devices in the Photos app, you can backup and restore iOS devices, you can use Universal Clipboard allows you to cut on one device and paste on another, you can sync Messages and other services too.
iCloud needs to sync with local files and so if the local files are deleted or corrupted, the same thing will happen to the synched files on iCloud.
Delete on one place and it is deleted on all is true of any synchronisation service including OneDrive. However, you can Recover deleted files on iCloud.com for up to thirty days so they are not irretrievably lost when one month has passed. Additionally a wise computer owner will have a backup regime and Time Machine is built into macOS for local restoration in the event of data loss - or migration to a new Mac.
See more at iCloud - Official Apple Support
