Plenty of superheroes get magic powers and suddenly have the ability to do incredible things, regardless of learning.
The only thing Rey does that strains believability is the mind trick, but that’s only because we’re familiar with how the force works and we know that you typically need a good deal of training before you can accomplish that. But the film presents Rey touching the lightsaber as awakening the force within her. It’s different than what we’ve seen previously in the series, but it’s not so different from the origins of many modern superheroes. Whether the lightsaber should have these abilities is another debate. This is a fantastical franchise so I’m inclined to not mind. The force works in mysterious ways and we could find out next film her fast skills in it are strange in universe. But it seems like a different debate than whether she is a believable character, and it’s really a debate that should have nothing to do with her gender.