Your post is most likely just trolling. But in case it's not i will ask you follow ups.
-Define what character development is and what should happen to obtain this development.
The rest of your points are purely based on your own personal opinion. You are entitled to your opinion. But if you dislike everything this manga is why waste your time reading it? Also, all of these problems you pointed out exist in every other manga. So it seems more like you just dislike manga as a medium than anything else.
I dont understand where this statement comes from or what it is trying to say. Are you suggesting that nobody may speak or write about anything unless they conduct their own primary research or have experienced it first hand? I would say that reading books and educating yourself on a subject before writing or speaking about it is what everyone should do.
Also, its a story. It in no way reflects real life.
I have to explain character development for you a simple google search would have sufficed.Let me do the honors
The change in characterization of a dynamic character, who changes over the course of a narrative. A simple explanation via the help of wiki.
The only person who has anything substantial change is Usopp everyone else is underdeveloped which the main character being among the worst.It is a fact that Luffy is the same as he was from the beginning of the manga,he is a static character.Luffy is a Goku clone.
To address the next point background information regarding such sensitive issues should be done,other wise it will just make him look like joke since he has no clue how to deal with it.