Yeah I should clarify; I think it's well past the time of sh.
Still, sh is unrivaled for portability and brevity/velocity; I wouldn't swap virtually any the shell scripts I've written for python scripts. I think sh is a decent and often well-suited tool if you can manage to wield it properly (not a straightforward endeavor).
I look forward to checking out oilshell though, so thank you~
Edit: FWIW for arrays in POSIX sh I generally only use:
http://www.oilshell.org/blog/2016/11/06.html