Like Unix you can't grok all of it (ever), but you won't ever need all of it. Just learn more of it as you go along. See it as a trip :-)
And if you need your Emacs Clojure development environment right now, have someone make a VM for you.
...and customized it enough to have an environment comparable to what other editors ship out of the box
wc -l ~/.emacs.d/init.el
241 /home/dario/.emacs.d/init.el
241 lines of emacs lisp, and I'm still unsatisfied with the current state of my emacs ls -l ~/.emacs.d/emacs.org
-rw-r--r-- 1 user user 67417 Oct 1 17:01 ~/.emacs.d/emacs.org
And after 15 years I'm getting finally somewhat satisfied. However, the alternatives were always worse.The ctrl+spacebar and search way that Light Table works, while not the fastest, was still preferable to holding down multiple modifier keys.
All that being said, the source of my hand pain might actually have to do with my neck and back, as working on those areas has substantially relieved my pain. So perhaps that will no longer be a barrier to emacs usage in a few months. :)
I've never used the defaults[1] for long. First by making my own custom keybindings, then by making keybindings compatible to what most others applications use and a couple of years ago by switching to evil-mode. I already had vi/Vim experience so that was pretty optimal.
[1] Except some really basic ones that I also use in the shell: C-a, C-e, C-r, etc.