creative_minds:
First of all, I think it's a potentially interesting and compelling story. I googled slave rebellions in Jamaica and see that there was one in 1760, Tacky's Rebellion. But I see your story line is significantly different. I'm okay with that although I am curious to know why you did not choose to dramatize one of the historical slave rebellions.
Now then, the substance of your logline. As I noted earlier, your logline seems to state two goals: free his family; free the others. But a logline is about a plot and a plot should be about one and only one objective goal for the main character. (That dictum dates back to Aristotle's Poetics and it still makes practical sense. Yes, a movie, and even more so a mini-series, can have multiple story lines, but all the threads should be framed and organized with reference to the ONE objective goal of the protagonist.)
In your story, the main character is the warrior.
That the warrior would want to liberate his family is a no brainer. But then I put myself in the mind and context of a 17th century man living in Ghana and asked: in an era of primitive communications when it took months for information to cross the Atlantic, how likely is the warrior to be aware of how horrible conditions are thousands of miles away in Jamaica? He may have heard rumors, but how could he know how bad conditions were to trigger his wrath and resolve to liberate all slaves in Jamaica, not just his family?
But then I thought of it from another angle: What if his goal, while still in Ghana, was to free his tribe (which would include his immediate family but also his extended family, aunts, uncles, cousins, in-laws) whom were captured en masse and sold into slavery by a rival tribe? Which happened all too frequently in that period. Loyalty in 17th century West Africa was to one's tribe -- not to one's race. (And even today, loyalty to one's tribe often trumps loyalty to the nation state.)
So I find it credible that he would make the journey to free his tribe -- his extended family. But I don't find it credible that he would embark on the journey with the explicit goal to liberate everyone else of his race, slaves from other tribes.
(Although once he gets to Jamaica and sees how horrible conditions are AND realizes that he needs the help of other tribes to free his own tribe, his tactics change. But not the objective goal: liberate his tribe.)
So, here's a first iteration of a logline based upon my understanding of the concept and the historical period:
In 1656 a Ghana warrior embarks on a perilous journey across the Atlantic to liberate his tribe, kidnapped and forced into slavery on the sugar plantations of Jamaica.
I think it is important to specify where he's starting from and where is destination. It gives the reader a sense of the dramatic sweep of the story and how much struggle and risk is entailed in the journey.
And to reiterate, after he gets to Jamaica and sees how awful conditions are and that he needs to enlist help from other tribes, then liberating others becomes credible. As a MEANS to his ONE objective goal: liberate his people.
Don't know if any of this makes sense. Hope some of it helps.