Y’all is a contraction for “you all”, therefore is most certainly plural.
If you have ever a situation where it seemed that a single person was being addressed as “y’all”, it is far more likely that the speaker as addressing the person as a representative of a business, organization or specific group of people, therefore, it is still a plural usage.
“Y’all come back now, y’hear?” seemingly addressed to a single person is actually an expression that means that person and his or her family is welcome for a return visit.
I live in New England now, but I’m a 14th generation Virginian. I don’t use my Tidewater accent outside of family situations as it is likely to be misinterpreted that I am unintelligent or worse.
Don't be ashamed of your Tidewater accent -- that is very upper crust, along the lines of a Charleston accent. You want to CULTIVATE that!
Northeast Alabama accent, not so much . . . . fortunately I can 'do' both a rural and an upper crust Southern accent, depending on my situation. My sainted white-gloves-and-pearls grandmother from Augusta GA made sure of that!
Since I'm that rare bird, a second-generation Atlanta native, I have very little audible Southern accent. Real Atlantans don't - that's how we know each other in the crowd of offcomes in the ATL Metro, that and the pronunciation of "Ponce de Leon" (although if you want to identify an Atlantan of my mother's generation, ask them to say "Piedmont".)
It means that you and yours are accepted and welcome. Family ties are just automatically assumed. It's the veritable 'n em in mama'nem. Literally, mama and them.
I've heard that all my life, mama'nem, but it never fails to amuse me. Thoughts of sainted mama with her entourage, perhaps in procession with attendants, maybe a long cape, lol.
I am native Californian so I know nothing about the contraction “y’all” except that I like it. I have been told by more than one person that “y’all” is singular and “all y’all” is plural. That defies my logic, but logic has nothing to do with dialect that becomes adopted.
I don’t know the truth, but due to the disparity between what you are telling me and what others have told me, perhaps “y’all” is used as plural by some and as singular by others. I have most certainly been told it is singular and plural is “all y’all”. Take that for what it is, because I would not at all be surprised if various people or areas of people from the south of USA use it differently, some singular, some plural.
I understand clearly that “you all” or “all of you” is plural. It can’t possibly singular. I know y’all is a contraction of you all. But I have been told by some southerners that y’all is used in the singular, so apparantly at least some people use it that way.