Nope, I didn't. But if I could tell my past self to, I would mention that it's not really all that long, it's well written, and there's a lot of interesting information in it that would have saved me significant amounts of headache in the future.
Therefore, that's the first thing I think anyone should be taught. I understand there are many like you (and me) who jump in. I now think that not reading through the manual a bad idea, as I've seen the results of it commonly in these forums over the past ten years.
I also understand how it might have been difficult to find. But if you actually did read through the manual, this post wouldn't have been necessary since it would have been a thing that you knew existed. Even if you didn't quite understand how to use it at first, you would have known it was a thing and then looked it up again when it could have been applicable.
Sorry that's a little bit of an off topic rant. I think containers are a very useful shortcut for a very specific thing, but you can work fine without them. I don't really think they're required knowledge compared to multitudes of other things like picking, how the event sheet works, expressions, loops, and arrays.
Arrays would be my specific topic of choice to introduce outside the beginner tutorials. I die a little inside after every post where people are intimidated by the concept of arrays, when they're so useful and basically just spreadsheets that everyone is actually already familiar with. I blame high school array/matrix math for the confusion.