Well that’s not entirely true. Luke wasn’t some random nobody. It was established in the first part of the film:
“I want to learn the ways of the force and become a Jedi like my father.”
So the force was already strong in his family, with or without Vader being his father.
Was it? Let's look at Star Wars purely in a vacuum... Poppa Skywalker (let's not call him Anakin at this point) was not the one that the fate of the galaxy was predicated on. In fact, Obi-Wan really plays down the concept of being a Jedi.
LUKE: No, my father didn't fight in the wars. He was a navigator on a spice freighter.
BEN: That's what your uncle told you. He didn't hold with your father's ideals. Thought he should have stayed here and not gotten involved.
LUKE: You fought in the Clone Wars?
BEN: Yes, I was once a Jedi Knight the same as your father.
LUKE: I wish I'd known him.
BEN: He was the best star-pilot in the galaxy, and a cunning warrior. I understand you've become quite a good pilot yourself. And he was a good friend.
He was a Jedi, a friend of Obi-Wan, who was killed along with a large majority of Jedi. The idea still was that a hero could be anyone and that was Luke. Nowhere does Obi-Wan suggest that having a biological connection in order to make someone strong in the Force.
LUKE: The Force?
BEN: Well, the Force is what gives a Jedi his power. It's an energy field created by all living things. It surrounds us and penetrates us. It binds the galaxy together.
AND
BEN: You must learn the ways of the Force if you are to come with me to Alderaan.
There was no concept that the Force made someone superhuman, that it was any kind of a destiny. Luke tapped into the power with a little bit of training. In fact, if you consider the light side of the Force in Star Wars, really all it does is influences things -- the Stormtroopers on Tatooine and the Death Star, it allows Obi-Wan to feel the destruction of Alderaan, Luke to feel the training drone, to know when to fire his torpedoes, but what does the light side do beyond that?
At the same time, the dark side seems to be more powerful, yes, but perhaps is a slippery slope.
LUKE: How did my father die?
BEN: A young Jedi named Darth Vader, who was a pupil of mine until he turned to evil, helped the Empire hunt down and destroy the Jedi Knights. He betrayed and murdered your father. Now the Jedi are all but extinct. Vader was seduced by the dark side of the Force.
AND
VADER: Don't be too proud of this technological terror you've constructed. The ability to destroy a planet is insignificant next to the power of the Force.
The problem that I have with both Rise of Skywalker and to be honest, to a lesser extent, Empire/Jedi is that it makes the story more of a family squabble that causes the entire galaxy to basically be fighting for the Skywalkers vs the Palpatines.