CentOS is how RedHat releases their sources in compliance with open source licenses (Presumably they're going back to releasing them as a consequence for this).
My familiarity with Amazon Linux is about 4 years out-of-date these days, but it was a RHEL/CentOS clone with a number of the core libraries like glibc being updated and maintained by Amazon on an independent life cycle.
Not really. You can use Alibaba Cloud Linux 2 like that if you want but why would you do that? Oracle Linux, CloudLinux, Debian or openSUSE Leap are better choices.
