It makes no narrative sense in TFA to let Finn ever have the lightsaber unless he was meant to be a Jedi as well.
Why? Because it is only given to him after Rey has her Force vision, we - the audience - already know she has the Force at this point so pulling in a second character - Finn - makes no narrative sense unless he was meant to be a Jedi as well.
It makes even less sense for Maz to tell him to fight with it as he had a blaster rifle moments before this sequence, so he did have a weapon but the story strips it from him without any explanation to give him the lightsaber. A Jedi’s weapon.
So all marketing aside. It makes no sense in the story for Finn to fight with the lightsaber, to purposefully be given it, if he was never intended for the Jedi’s or a Force users, path.
Another thing is when Maz gives Finn the lightsaber she does not tell him what to do with it, such as give it to Rey or Luke or whatever, she simply gives it to him
Exactly!
When Maz hands the lightsaber to Finn she says, “Take this, find your friend”. Find your friend and what? Protect her with it? Give it to her?
Again this happens after the Force back, so there’s no narrative value in the ambiguity if Finn doesn’t also have the Force. It would have taken JJ nothing to have the line go “Take this, find your friend and give it to her” if that was what was the intention the whole time, because the mystery of Rey’s Force sensitivity is pretty much already resolved for all but the densest of the audience.
So to all that goes “well it’s the marketing’s fault everyone thinks Finn has the Force when he doesn’t”. No, it isn’t. Sure it isn’t helping, but this is 100% the story’s responsibility, if Finn wasn’t intended as a Jedi this narrative misleading is completely and utterly pointless and downright cruel.