Not sure “So” is actually a meme it’s more a grammatical device, it’s not in the same class as "um" or "er" if expressed in writing, but it has “evolved” and I’ll use another example to make my point, Spurious is an interesting word it has several contemporary meanings, one of which is in biology, but its origins lay with roman military law, legionaries were not allowed to marry, any children produced by legionaries were wards of the roman state, they were acknowledged as SPQR (Senatus Populusque Romanus), this later became spurious offspring (bastard) in the middle ages, which is now used to mean anything from random event to counterfeit depending on context.

So, originates from the Hebrew and later Greek and Latin for “amen” its original use would have been “so, I will go to the next town” (god willing), today it has a different connotation, it is used to highlight something or someone questionable as in “yeah, that’s what his so called friends thought”, or it might be used to introduce a new phrase or concept as in “so-called 'super bug'”. When it is used in “so, let’s look at the next power point slide”, it amounts to little more than punctuation, a place holder or pause, its habit more than meme I think, if it were not “so” it may well be “erm”, “er”, “OK” or “right”, does that makes sense?