Do you have to be intelligent to develop AI?

You need Statistics to understand machine learning, then of course one may learn some concepts by hearth. I am not sure then he could "develop the new AI" though.

There is a difference between doing AI Engineering and AI Research.

By the way, I still don't know what IQ really means in the sens of what's the difference knowing and IQ? I think success in research in general is a mix of knowing, dedication and luck.

  begin with "You don't need a lot of math" so their recipients are not supposed to be very smart

I would be weary about correlating high IQ with a high maths aptitude (and also of the reverse) -- since other things effect maths development more than IQ (The type of teacher you have, etc.); I had the pleasure of knowing quite a few people in MENSA over the duration of my childhood, and I can assure you that many of them had exactly the same problems with mathematics as the rest of the population.

I disagree that a high IQ is a necessary component of developing an AI (And I assume you're talking about Strong AI here); I would say that an expert in the field has a much better chance than the average developer, but since nobody (To my knowledge) has created a general AI we can't really know for sure.

It would be interesting to see if AI researchers (or mathematicians, for that matter) tend to have a high IQ compared to other fields/jobs...

Perhaps my idea is that machine learning and AI is now a way to sell snake oil, specially when you try to give recipes and avoid the foundation. Today computer programs can do many task as for example predictions using models which require little o no tuning, so the user just press a button or write two or three lines of code. Someone can think that he is at the cutting edge of research pressing those buttons, perhaps that naive feeling is what I was fighting again.