Can one recover from an accidental rm -rf of system directories by copying those files back in from a backup?

Well I’ve joined the “accidentally trashing your system with rm -rf” club! Luckily I didn’t delete my home directory with all the things I care about, but I did delete /boot and /usr, and maybe /var (long story, boils down to me trying to delete non-system directories named those but reflexively adding the slash in front when I should not have). I have backups of those as well, so what are my prospects of recovering from this by just copying them back in using a live USB? Only issue is they’re stored in my server as belonging to the server user (I assume everything in those directories should belong to root and I can just use chown?) But I also don’t know if they retain the same permissions when backed up.

Has anyone had any luck recovering a system in this way? I’m hoping not to have to reinstall everything because I had gotten pretty cozy with the current installation.