I was struggling a bit with the distinction between inputs and parameters (also in the make API). Both are inputs to a computation. I guess an input is a file dependency, whereas a parameter is a non-file information dependency.
I cannot provide a recommendation for better names -- just going on record that this causes mental friction for me.
This a concern initially raised by @mih:
Suggestions by @christian-monch:
variable
template-variable
script-variable