I am a Chinese native speaker, and I don't know much about Chinese grammars, but I can use my native language with full confidence in writing and speaking. For the same reason, I think we do not need to take English grammar learning so seriously. In my opinion, so-called grammar is just needed to describe how the language is used today, not needed to give some perspective analysis of the complicated structures. English, same as other language, is not a static entity, but is continually changing according to the society changing. Those changes is reflected in its so-called grammar.
In summary, do not take English grammar so seriously, and just focus on how people use English today.