Regarding lightsaber fighting specifically, the movie shows us Rey is already well-practiced defending herself with other melee weapons, and in TCW (which has the ‘George Lucas Seal of Approval’) and also in other new continuity media like Rebels and Mando we see non-Force users wielding lightsabers/the darksaber, so presumably Rey’s ability to hold her own against Kylo (who is injured and not actually trying to kill her yadda yadda yadda) with one in TFA is just transferring over that general skill. If she was accurately deflecting blaster bolts with it or pulling off lighting-fast prequel-style choreography that’d be a stretch, but IIRC she basically just swings it around.
I agree Also, to add to this point, she spends most of the fight losing and only turns it around at the last minute of the fight. Force skills are one thing, I can understand people’s complaints about her picking it up too easily, but her fighting skills aren’t. Why do we need to see her learning how to fight before she’s able to fight using a lightsaber? The lightsaber is only special as it is the weapon of the Jedi, and it’s a really powerful light sword, if you’re already skilled in using other weapons I don’t see why a lightsaber should be more difficult to use as it’s essentially a sword. And we don’t need to see Rey learn how to fight with her staff, That’s Literally The Point Of Her Introduction. She’s introduced as a scavenger on Jakku, we see her life of scaling old empire ships to find parts, we see her sell them for food, we see her wall of marks detailing how long she’s been on the planet, we see her fend off someone trying to steal BB8, we hear her say her parents left her there and are coming back for her, and we see her being left in a flashback so we know she’s been doing this since she was a kid, and it’s done to show how she’s picked up on the skills she uses throughout the rest of the movie. So we don’t need to see her learn how to use a lightsaber, we already know she’s skilled with staff and we know why she can fight using a staff, she needed to in order to survive, we don’t need to see her learning the skill cause it’s not necessary to show. This isn’t the case of someone who has no fighting skills besting a character who has tons of skills from years of training. Both Rey and Kylo Ren have years of experience with using weapons, Ben the lightsaber and Rey the bo-staff. It doesn’t surprise me that they could be more equal in skill despite Rey not having formal training because Rey needed to learn these skills to survive on Jakku and not die on the planet and Rey transfers the skills she has with fighting with a staff to fighting with the lightsaber because when you are skilled and capable of using one weapon it’s way easier to use another one even if there are differences between fighting with a staff and fighting with a sword. She’s obviously more skilled at using the staff, but she can use a lightsaber because of this. Also, Kylo Ren is heavily injured due to getting shot by Chewbacca. That’s why she has those skills at the end of the movie and that’s why it’s not really a problem that she’s able to defeat Kylo Ren
And to anyone saying this is mental gymnastics, no it’s not it’s film literacy. All of this stuff is communicated silently in the movie unobtrusively by way of visual shortcuts. The opening of the movie uses deft visual and storytelling shortcuts to establish Rey’s character, her skillset, and why she has these skills. It does it by showing what her life is like on Jakku, the skills she has from living on the planet, and her character motivation all without much exposition. We see Kylo Ren get shot and the film makes sure to remind the audience of this fact by showing the injury and Kylo hitting himself in that injured spot a few times during that sequence. We don’t need someone in the film to say that Kylo Ren is injured as we can see it and the movie makes sure to remind us. We don’t need to have exposition on why Rey has a lot of skills from living on Jakku, and we don’t need to see her learn these skills either, the movie does it by showing the audience via her introduction the implied amount of time she’s been living on there. Sure not everyone is going to notice this stuff. And also most people if they do notice it, notice it subconsciously, and because of this it’s way more difficult to explain how they know it to other people. Do I have my complaints about Rey as a character, sure I do, but I think the movie gets more right with her character than it gets wrong. The movie does establish her own skills and why it’s not such a stretch that she would be able to defeat Kylo Ren at the end of the movie