I think you're lucky with your son. The meds and interventions are essential for some. End even then the progress isn't always visible. Speaking from a different experience than yours.
Many years ago I remember using a similar shim on ASP.NET where you'd simply decorate a server-side C# method and you could call it from JS like any other method. Not quite the way done here, but it had similar goals to blend server and client. So far, these things don't work in practice because of the so many things that differ between a browser and server environment.
I’ve seen videos and read lengthy articles about the internals of OAuth a few times. Mo has done an exceptionally good job to keep it bare minimal and used a simple analogy to explain a complex topic. Definitely recommend spending a few minutes if you feel wtf about OAuth.
May I say, look at SpyREST (SpyREST.com) if you consider developing the API first and then produce the documentation automatically simply by exercising the API? This is an open-source tool, feel free to take a look.
I'm developing SpyREST and will be happy to discuss if you want to learn more.
I am not sure of its origin. But these days you'll find good ORMs that would craft the query for you. My point is, the Mongo API seems to be more of a machine readable API with the $ keys used somewhat in a hacky way.