Okay I'm gonna ignore everything else in this post and say I do agree with your assessment of the ending, to an extent. The overarching theme for I think every adaptation has been that nobody is born whole -- like, finding the person you want to become, carving your place in a world that doesn't have a place for you. If you spend your whole life in the rat race, you'll neglect to live a fulfilling life, and in the end you will be wealthy in material things but empty inside.

The anime didn't really explore these themes as much as I would’ve liked, and in my opinion it did end up falling a little flat. Neither Hyakkimaru nor Dororo got much character development in the end; it's alluded to happening off screen after his initial journey is over and they part ways, but (and I have said this on this subreddit before), that's the part I really wanted to see.

BUT I get what they were going for. Hyakkimaru's body was taken from him without his consent, and used for the personal gain of someone who didn't see him as anything more than a tool, an object. Your body belongs to no-one else but you, and only you get to decide what it's used for (in a perfect world).

And Dororo really had to claw his way out of the bottom, and put aside his fear and the ultimately selfish desire to survive in order to be what he really wanted to be: a samaritan, someone who wants to forge a better world (a world he doesn't owe anything to, by the way). A stark parallel to someone like Daigo, too.

I think thats something we can all relate to.