Permissions on mac HD "read only", but work as read & write

Got a new computer (used), has an SSD as the main drive. I did a wipe and clean install of Sierra. When I "get info" on the Macintosh SSD, the ownership and permissions show 3 users: system, wheel, and guest. Nowhere does it show my actual admin username (although it does on my other internal drives).

It also says I have "read only" access, but I can clearly read and write to the drive, and have done so many times. Screenshot below from my main SSD, and also from another internal drive that shows proper users and permissions.

Is this anything to worry about? Should I try another wipe and clean install of the OSX? Everything is working, but I don't want to load up all my programs if I'm going to run into problems down the line or even if there's something wonky going on. I did a terminal command to repair permissions on the "home" folder and all was good, just fyi