...

He embodies the Idealistic super hero. The one whose goal is to keep the peace; to maintain due process; to ensure traditional justice is carried out.

Dr. Fate

He's the mentor. The rock, no pun intended, in which the other characters find comfort and strength. 

Adriana and Son

I'm going to ignore the son character, because he serves the same thematic purpose as Adraina. The only thing he adds is a connection between BA's past and the present. He serves as a reminder to BA of his own son. Although this doesn't come out very well in the script.

...

I think I'm going to stop here, as these characters are the only one ones necessary to drive forward the plot forward in its bare essence.

As you can see what is missing is a character which can bring forth the theme of the movie such that we do a lot more showing than telling. 

Unfortunately, the theme primarily comes out via dialogue. Adriana admonishes the Justice Society for not caring about the injustice taking place in Kahndaq. She brings forth the theme of what Justice should look like? Should it be dark and swift, as what BA does, or should it be methodical and by the book as what HM does.

What we need is a way to show these two opposing points of view, rather than just tell the audience about them.

What we need is a Reluctant Judas

Reluctant Judas (RJ) and the Theme

I would cut out or reduce greatly the role of Adriana's son, to just comic relief. And add RJ, who starts off helping Adriana out with her quest, but at the same time, he's feeding intel to Ishamel.

Ishmael would be more of a background character, who is directing Intergang from behind the scenes.

We could build up a relationship between him and Adriana, thereby his betrayal is all the much worse.

RJ is not blind to the injustice in Kahndaq, but he has lost too much, and just wants to exit this place. Something, which Ishmael promised him, if he gets him the crown.

In RJ's journey we can see how he's both bad and good. He cares for Adriana, but at the same time he can't waste the opportunity for a better life.

RJ's demise would come in the middle of the movie. When things go side ways he facilitates the Andriana's son's kidnapping. In retaliation, BA extracts the information he needs from him and kills him in front of Adriana and against her wishes.

This simple act of killing someone Adriana cares for, even though RJ has "sinned" against her, will really bring out BA's dark justice. And will make Adriana fear him, more than like him. She knows that she needs him to save her son, but at the same time fears his unpredictable violent nature.

BA killing RJ will be a precursor to him almost killing Adriana's son by mistake, and therefore, making his decision to give up his power a lot more impactful.

The addition of the RJ character will also focus the script. 

We're not going to have to waste time with Adriana's son. You can still keep all the jokes, but cut out the rest. The boy can still serve as a reminder of Black Adam's son. 

But we would build up a friendship between Adriana and BA. This friendship can be used as a vehicle to bring out the hurt and the guilt BA feels. This friendship story-line would culminate at the movie's mid-point when Adriana's son gets kidnapped, and BA kills RJ after he gets the information he needs.

Through the Ishamel/RJ interaction we could better understand the motivation and politics of Intergang.

I would also cut down the time spent with the younger members of the the JSA. In fact I would cut out the wind girl completely. And keep Atom Smasher for his comic relief .

Then I would use the time saved there to delve more into the Adriana/BA relationship and the Ishmael/RJ interactions. Flesh out the RJ character and make the audience empathise with his motivation. The audience won't agree with him, but at the same time, they wouldn't want to see him die.

The rest of the action and main elements in the story can stay the same.