Cannot upgrade from Mountain Lion higher.

I’ve had to clean install Mountain Lion (through factory reset), after a power outage wiped my hard drive. I’ve been unable to connect to Wifi since this happened (I’ve exhausted options with others on this site), thus as a last resort I thought updating and upgrading the operating system might fix this issue I’ve had. First I tried OS El Capitan, which I downloaded from Apple under their advise to do so before OS Catalina. Just like Yosemite, which I tried after that failure, I had the same experience, where it finished installing, however, there was no request to restart the computer, and after I did so manually, the OS is still 10.8.5... Before installing I thought it was weird that it said that the OS upgrades would only need 6mb of space.