Is iCloud a safe way of storing imporant data?

Hello.

Recently a very important external HDD died and I lost MANY important files! Mainly work files.

I've been using iCloud since year 1... but I never thought of it as a cloud service (like Dropbox or WeTransfer). I always thought of it as a safe way of synchronizing personal data between Apple devices. Nothing more. I do realize that as of 2024 my way of thinking is quite outdated... so this is why I would like to ask the following:

is iCloud a safe way of stories inDesign, Photoshop or Illustrator files? Is it a good way to store photos and videos for a larga amount of time? Also, is there a way of making sure that some files stay stored on iCloud BUT DON'T SYNCH with all of my Apple devices? For example: I can access them on iCloud on my Mac, but they don't don't synch with my iPhone?

I'm sorry if my question sounds inexperienced or dumb... but I really need some guidance from the good people at the Apple forums.

Thank you.

P.S.: I'm currently on a VERY old MacBook Air... so I have only Big Sur. But next month I'll be buying a new MacBook Pro M3 Max... a current model which will allow me to have iCloud+.