The "Bitcoin and Cryptocurrency Technologies" on Coursera helped me gain an understanding cryptocurrencies. Until I took that course I knew very little about the subject.
It's possibly a little dated now, but it's a good primer.
Not a cryptocurrency course per se, but Dan Boneh's course on Cryptography[1] is an excellent introduction to most of the building blocks of cryptosystems, including the technology underlying most cryptocurrencies.
In terms of level, it is more than a little technical (programming exercises in both cryptography and cryptanalysis await you!), while still remaining far from rigorous (compared to, say, a graduate-level cryptography text).
It's possibly a little dated now, but it's a good primer.
https://www.coursera.org/learn/cryptocurrency/
I'd love to hear what other cryptocurrency courses others recommend.
As many others mentioned, Andrew Ng's course on Machine Learning on Coursera was also very good.
https://www.coursera.org/learn/machine-learning