Available resources for learning WordPress 4.7.2 from the ground up?

I recommend the Theme Handbook of the official page, try creating a Theme using all of the features that are there, each one comes with example code, try copy pasting and adapting it to your theme.

The same with the Plugin Handbook try creating a plugin, reading the blog is good too, specially the development category, you can see how WordPress evolved and what new features and changes occurred.

Like in the post you mentioned the codex and the actual code are still a resource, i would add to it the developer search, which is great to search for function, classess, methods, hooks etc.