Ok, so I've just watched. This is just like what happened with many other anime adaptations to the big screen / live action. See Dragon Ball Z into Dragon Ball Evolution for example. They take "creative freedom" when they adapt the story and they change a lot of things. The original creator is mentioned because his story is the base for the adaptation, but the screenwriters are different.
The 2007 live action has a lot of things different to the original anime.
Dororo is an old teen not a kid like in the anime. Dororo's name is given by Hyakkimaru. This doesnt happen neither iin the 2019 nor in the 1969 anime. The way Hyakkimaru's body is rebuilt by his adoptive father is different.