Thank you all for this great thread. It’s rich in ideas and point of views.
If I may add something, education is not a one-side-fits-all. So, what a good first language to learn is depends on many different factors.
- How the student is.
- What education background they come from.
- What they are trying to learn.
Or, to be more cheeky, not everyone is a freshman computer scientist trying to become a software engineer. 
I did teach Julia to university students with no programming background. They were in a path toward becoming “applied data scientists”. And they needed to learn how to wrangle data. They also needed to learn that most concepts and techniques in data wrangling are not language-specific (i.e., no, data frames are not just R things, and no, web scraping is not just a Python thing). Julia was a great experience (and I started teaching this course in 2018, so there was still a bit of instability in the language).
One great thing for them was the broadcasting and the fact that loops are not slow. That allowed for a “we build a function for an example input, and then scale to many inputs” kind of workflow.
In general, for students coming from a strongly mathematical (largely written) background, Julia is very pleasant as it lowers the jump from “how I would think and write this in mathematics” to “how I would write it in Julia”. They don’t usually care so much about “the machine” nor whether Julia is dynamic, OO, functional, compiled, … Maybe some will get curious, but others just want to code to prove their ideas. They are not becoming software engineers, they are becoming mathematicians/statisticians/biologists/psychologists/… who code (sometimes very well, and very complex things). And you don’t want to enter a classroom of biologists and try to teach them C.
PS I don’t teach that course anymore but I’ll be teaching one on Data Engineering next semester, where I will try to include as much Julia as possible, send me ideas 
if you got any or you are keen to be a guest.
PPS there are biologists who are C wizard and witches, and would code you up a storm, no disrespect meant. It’s only a question of priorities.