I am not talking about quirks. I am referring to purpose of introduction to slavery. While OP demonstrates how sever and multidimensional racist issues can be it fits OP because of the type of the story- it deals with discrimination of different classes and racism of nobles and what not. But Naruto is tackling a different issue i.e. how our pasts shapes our present choices and way of thinking and that only after embracing our past and letting go of the hate we can move forward. So comparing who detailed which theme more like this is kind of meaningless.
OP always introduces big arcs episodes. Naruto has a somewhat a minimalist approach where instead of spreading the issue to a lot of insignificant unforgettable characters he expresses the issue through a fewer but impact characters.
Moving forward from one's past, is not a big progressive theme. that's just a life lesson you should have already learned. I'll make a quick list. Feel free to add.
Naruto's themes:
Hold friendships no matter what because they are special.
One can change their ways.
Unity is possible through mutual understanding and cooperation.
The collective is more important than the individual while at the same time not forcing it upon them.
Naruto's unintentional themes.
Everything is preordained.
Only the special matter.
Criminals get off easy if they do one good act.
How Naruto affected our world:
be a good friend and talk things out
One Peice themes
Self-actualization is important and taught to the audience to be important.
No matter how different you appear, you are a person.
Everyone has the right to be free ----what is a pirate? and person who is free, right?----
Everyone is an individual.
Friendship is important and necessary to survive.
Men can show emotions to the world. the guys cry more than the girls.
The old days are over, let the new age begin. <---------
Even a world authority needs to be checked
One Piece unintentional themes/topics
Girls look over sexualized. nami, robin, almost every girl. "but why is that bad? think about that. they are pirates and/or live in a pirate era"
Girls need to be saved.
brute force is the only way to beat the bad guys
some characters fit racial/stereotypical art styles
a few sexist jokes
How One Piece affected our world: or at least tries to.
Demonstrate different humans, giants, fishpeople, minks are living, thinking "people"
Question authority.
Gender and apparently your biological *** can be chosen
Slavery is bad
being an as***ole is bad
Taking others for granted leads to a loss ------> Donflamingo<-----
Follow what drives your passion
Protect others ---- some marines do this too------
Help those who ask for help.
So is Naruto the most progressive mainstream manga? it really only has one thing going on, if every person is good, the community is good...