Will this be overkill or otherwise not recommended for someone who is new and just starting to learn?
My goal is to have something I can grow into, but initially I'd like to host a few VMs, game servers, and a have place to store content. I'd also like to host a PLEX server in the future as well but might buy a separate piece of hardware for it specifically down the road. Thanks in advance for taking the time to help a newbie!
The machine OP linked has E5 v1 CPUs, which are a 12 year old Sandy Bridge-EP chip that's hugely power inefficient by modern standards and tops out at 12 cores per socket. E5 v4 would be Broadwell-EP, which is still 9 years old but benefited from 3 more generations of PPC and efficiency enhancements and tops out at 24 cores per socket.
IMO, that's as far back as you can go in search of cheap and cheerful hardware without shooting yourself in the foot on performance and efficiency.