It's very useful to use ShellCheck to check any shell code you write.
The proper she-bang for Bash is
Pure Bash Bible - Collection of pure bash alternatives to external processes.
Bash Infinity - Modern boilerplate / framework / standard library for Bash.
Funky - Takes shell functions to the next level by making them easier to define, more flexible, and more interactive.
create-bash-script - Bash script designed to create other bash scripts with argument parsing.