I would appreciate if you can check something for me. Install numpy normally in the script editor (not in site-packages). This should error on your machine as shown above.
Then go to this folder: (%HOMEPATH% is your home directory and default-* is the default environment in rhino python 3 deployment):
%HOMEPATH%\.rhinocode\py39-rh8\site-envs\default-*\numpy\core
Check to see if all these .pyd files are available.
The primary reason that this ImportError is happening, should be either one of these .pyd files are missing or security policies setup on your machine that stops them from being loaded. I am trying to confirm this