I used to play a lot of jobs that required the society club date/Jazz standards. This was the core of tunes that every working musician was expected to know. It originally consisted of basically show tunes, mostly played in the society beat, or fox trot tempo, and was augmented with Latin stuff. The body of tunes numbered between 1000 and 1500, depending on who was counting, with a core of essentials that is about a third of that.

Every one over a certain age knows most of them(and a lot of younger people, too), even though they may not be able to name them. The point is that they were familiar.

There are thousands of other popular tunes that people know--I've got a book somewhere with the hundred best selling US/UK records from each of the last fifty years, and another that covers the fifty years before that, but only a few of them have managed to achieve any sort of lasting place in the world at large--

At any rate, here are lead sheets with basic chords for about 400 of the most important tunes Ralph Patt's Vanilla Book. Learn as many as you can--