He's young, and could benefit from a more serious theoretical framing. Ng's focus is on the theory of statistical ML, but there's a whole classical side to AI and statistical learning is a subset. That's where I would want to look for theory. Most recent advancements in StatML just come from classical systems engineering permutations of the plug-and-chug ANN (let's cascade them! let's use different algebraic relationships! let's use frequency domain!)

P. H. Winston (RIP) wrote a very nice book, and course regarding AI and how it may arise from what are considered intelligent processes.

https://youtube.com/playlist?list=PLUl4u3cNGP63gFHB6xb-kVBiQ...

Unless you're simply trying to build or experiment some specific design, best not to fasten your mind to a specific tech stack.