"Jim",

I am certainly not Glaswegian - a fact gratefully acknowledged by all of the residents of that fair city that I have met.

"Jim" was a name in constant use in "The Goon Show" by almost any given character to any other. As in "Hello, Jim", pronounced in the high-pitched, slightly nasal voice that was the hallmark of the Goons.

An analogy is the Londoner's use of "John" as a form of casual greeting to anyone he has not met before (Yes, "he" - I have never heard a female use this form of greeting)

And, yes - I am a sort of Londoner - County of Middlesex in fact, which has long since been absorbed into Greater (!) London.