Can i restore a back up of the user folder to a fresh install without issues? Can i restore a back up of the user folder to a fresh install without issues?
I created the back up with the disk utility tool

I am fresh installing an iMac late 2015 because it's very slow.
I have backed up the /users/ folder and the /library/ folder.

I have a second question:
Is this a good way to handle this? Or is there any better way?
Would i be able to restore the users folder with time machine without bringing other applications etc?
How did you make a backup using Disk Utility? Did you mean you cloned your startup drive? If so, you did not just make a backup of your user folder you made a backup of your entire startup disk.

But to answer your original question...

The best way to do what your trying to do is to 


Make a Time Machine Backup
Erase and Reinstall macOS
Use migration assistant to restore from a Time Machine backup where you can select what content (Your user folder) you would like to transfer



Note: Usually I would quote all this stuff but this is pretty standard information so I opted to just link it.