HKEY_USER contains the sister entries to HKEY_CURRENT_USER. Specifically, HKEY_USER contains the user settings to ANY current user. Still confused as to the differnce between HKU and HKCU? Don’t be. What if you did a RUN AS command or a SWITCH USER? Where would that users profile be loaded and accessed? You got it: HKEY_USER. That is why each HKEY_USER key starts with a SID number (the long string of superficially random numbers that uniquely identifies each person that has a profile on your PC).
If you were the only person to log into your Windows PC since your last reboot, then you should only see a few short system SID’s, plus your SID.
You can verify that the SID you see in in HKEY_USER is actually you by checking PROFILE IMAGE PATH on each SID listed under HKLM > SOFTWARE > MICROSOFT > WINDOWS NT (note the NT!!) > PROFILE LIST. It’s fun for the whole family!