If someone is interested in array languages, I would start with learning q, then k, J, and finally APL. q and k are much more conventional and less complicated

If someone is interested in array languages, I would start with learning q, then k, J, and finally APL. q and k are much more conventional and less complicated than J/APL. They also tend to be more practical, and less mathematical. They also don't have multi-dimensional arrays, so the code tends to be both less general and less confusing. Once you've gotten familiar with them, J and APL won't seem as weird. Moreover, it's entirely possible to write regular procedural code in q and k, so it's easier to transition to the array language mindset.