I thought UNIX was case-sensitive from very beginning (though early terminals probably were not). Also digits/punctuation can be counted too, in fact '.' is a (shell) command.
Nobody I know in my cohort/age-group thinks capital letters make a different command. Lots of us inherited a memetic state of alias/function to make a single "l" do some variant of the ls command. And "m" for more was not uncommon. "p" to pass to the large for some, never bothered me much to type more letters.
Other than that, the "w" and . Are about it. . As an execution invitation feels less like a command than just syntactic suger.
(As does the cryptic :> to zero instantiate a file)