I love both characters but Rey does stand out more.
She is far from a cardboard cut out of a character. Characters do not need people dying around them all the time to create complexities. And some of the comparisons to Luke are unfair because people cannot decouple the ANH Luke to the trilogy Luke.
Rey is good at mechanics, why? She's a survivor, she's a loner it's do or die. More so then Luke she lives in a harsh environment where any meal may be her last, that was quite explicitly shown. She has no one there to care for her so she has to do everything her self. Her entire life is around scavenging mechanical parts for money. So yeah in the 12 years of doing that day in and day out she would learn a lot about parts and mechanical aspects of ships etc. So her telling Han what to do is not that hard to beleive and far from "perfect". She's good at that stuff because it's been her life. If there would have been a part that would have saved the crew knowing about moisture vaparators Luke may have done something about it. The two have very different backgrounds and I think many completely forget to take that into account.
One thing Kasdan said many times when JJ was working on TFA is show, don't "tell". Which many Nolan type of blockbusters and modern blockbusters go more heavy on exposition to explain things rather then observe it.
Rey is good with mechanics, and fighting with a melee weapon. She got punched right in the face by three thugs trying to steal BB-8 from her, she took care of them. Why? Because the world she lives in I'm sure she has to fight day in and day out to survive, it's why she caries that stick with her everywhere. Again it's such a do or die world she knows nothing else.
But as for everything else she's not really that great at things. She's actually more flawed then Luke (comparing ANH to TFA). Luke is a little whiny and rejects the call to action by the gods only once but then turns around and accepts his duty. He's someone that always wanted to leave, and get out of his world. Where Rey is the complete opposite someone wanting to stay in a fools hope that her family will come back for her.
She actually continues to be a coward throughout the majority of the film. Running from everything, not wanting responsibility not wanting to accept her fate. It's not until the last 10 minutes of the film when she grabs the lightsaber that she actually takes responsibility into her own hands. Where Luke did that and accepted his fate in the first act of the film. On top of being a coward she's not that great at "everything". The little subtle things show this. When flying the Falcon she runs over everything destroys half of the shipyard of Nima Outpost, if you watch the scene she is hitting the ground scraping against Star Destroyers etc. She gets some lucky breaks (as did Luke we are dealing with heroes of the Force akin to Hercules etc) she is not perfect at flying actually Luke is really good at flying compared to Rey. So again she's not perfect in that regard.
She was trained with a melee staff so we see that she puts it to use. But even fighting a very weakened and emotionally distraught Kylo Ren she's not very good. It was funny because I had to show a friend the duel and point out all the things she does. She is clumsy as hell, she falls to the ground multiple times, she is striking in awkward ways that Kylo just bats off. Now of course when she taps into The Force it guides her as Luke was guided to aim correctly. But lets not act like she was doing double backflips over Kylo and fighting like in the PT. She's still very slow and not super well trained. But again she was proficient with a melee weapon we see that early on, but she's still not that great and there are is much to show that.
However yes, most of these Force heroes overcome things that a normal person would not necessarily do. Luke learns after one sentence from Obi-Wan how to block laser bolts with a lightsaber. He infiltrates the most heavily armed base in the galaxy killing many Stormtroopers and escaping, destroys TIE Fighters and by the end he flies with an elite squadron and destroys said powerful and heavily armed base single handedly.
Heroes will always have more abilities then us. But Rey is far from perfect and again more flawed then Luke. Unlike many heroes out there Rey is a coward, which can be seen as a huge sin in "being a hero" . Also she is captured by the enemy (Luke is not) she is tortured multiple times and actually mind raped. She is thrown against a tree with the Force. She is punched in the face, treated like garbage by Unkar Plutt. Yeah she's not some "perfection" of a character.
Lastly when it comes to learning the Force as I said in the last page there are multiple ways to learn anything in life. Luke had a few sentences from Obi-Wan and was blocking laser beams with his lightsaber. But he's a natural so yeah he learns quickly. How does he learn how to use the Force in ESB before he sees Yoda? The Force is mysterious there is no instruction booklet or one way to learn. Just like in the real world as I said in the last page there are many ways. Some people learn by reading, some learn by a mentor some just learn by observation. Luke was taught more so which makes sense, he's a very sheltered individual that needs that mentoring more so than Rey. Rey is someone that has had the school of hard knocks. She needs to learn quickly or die. It's great how they show that she learns by doing and observing. She learned how to use the Jedi Mind trick is not any stretch what-so-ever. JJ even in his commentary talks about the very long scene with no dialogue between Rey and Ren when he's trying to manipulate her mind.
Rey learns in that scene very slowly but by observing what Ren is doing to her. Just like my good buddy when we all had to learn how to play Basketball, he seriously watched a game in rotary when we were kids and just picked it up faster and better than any of us (he's still way better at basketball then I am). Some learn by observation and Rey was intimately getting to learn what someone does to you when they manipulate your mind with The Force. So when I hear that complaint I don't get it. She does not learn like Luke, but just learns in a different way, both do extraordinary things because they are extraordinary people. But again Rey seems to be more flawed as a person, not wanting to be a hero not wanting adventure not wanting the call of the gods where Luke runs right to it like most heroes of old do. However Jyn is different then Anakin, Luke or Rey in which yes she is more of a "normal" person, she's not Force endowed and part of that greater fight of dark vs. light. They are equivalent to the heroes like Hercules or even most Superheroes. Jyn is the first main that is truly just a "grunt" in the world of Star Wars (not a slam by any means) So it is interesting and fun to see that.
But having said that I love Jyn as well. But my biggest problem with Jyn was some of the clunkiness of her arc. She goes from someone that is "I don't care about anything." to "We have to save everyone" mentality almost too quickly after the Eadu scene. And I would ask in all honesty what really is her character flaw? That creates that complexity? I never really saw as such in my eyes. However I think for the most part it works it's just with Rey, Finn and most the mains in TFA all of there moments feel emotionally earned. When Finn turns on Kylo, or Rey accepts her destiny those moments feel so earned and that they had a smooth arc that way. Where though the characters were good in Rogue One there was some disjointed feelings and a lack of intimacy that lost some of that earning of certain "ends".