Given that English lacks a familiar plural pronoun, the contraction y'all makes sense, even though I don't use it.
For example, in German, "ihr" refers to "you" on a plural basis. When you use "ihr," the listener knows you are referring to a group. So, y'all appears to fill a gap in current vernacular English. That's my story, and I'm sticking to it…y'all.
What an interesting comment! Got me thinkin.
English has the plural pronoun, "ye" similar to German "ihr." Ye was common english From way back. From the 1611 English bible, you will find besides the "you all"s some "ye all"s:
versus;
I have noticed in English law books in the 1500s and 1600s, they often just wrote the "Y" of ye or you, or even yet, and just put a small superscript e, o, or t with it to show what the formal meaning was. Here is an example.
From Helen Wood's English grammar reader, London, 1865, Ye is the common English second person plural personal pronoun, in a nominative case:
As I understand my old grammar, the nominative case pronoun is acting the verb, and the objective case is acted upon.
Mr. Gould Brown's grammar, London, 1860, seems to agree with Mrs. Wood, (refering to the 1611 edition King James bible):
Brown complains of the influence of Shakespeare, Milton, etc. in confounding the grammatical senses of ye and you, rendering popular speech SEEM inconsistent. Another commenter noted:
Many Americans understood the distinction of Ye and You, though. From Brandon, Miss., 1853, in the comical "Chronicles of the Fire Eaters of the Tribe of Mississippi:"
Anyways, sorry for the digression, but as regards your comment on German, from Fulborn's 1852 (Philadelphia) German-English Instructor, he directly translates English Ye with the German Ihr you mention:
From an 1863 English-German bible, we see the direct translation of Ihr and Ye:
So, back to "y'all," Montgomery and Heinmiller's "Dictionary of Southern Appalachian English" (2021, U. of NC Press), notes "y'all" is pronounced in either the familiar plural nominative (formally YE ALL), or plural objective case (formally YOU ALL).
I have some kin who yet distinguish YE and YOU a little bit..., more out of habit, pronouncing: "YE went and done it!", but would say "Who did that to YOU?" But if you asked them to spell it, in conformity with their school-marms instructions they would write out both with YOU.
Y'all take care.