She’s a snarky cutesy Asian girl. It’s mostly in the personality. D.Va also appeals to this demographic, though at least D.Va is offset by having some depth to her character.
I doubt Zen doesn’t understand so much as Zen is being purposefully cagey around anyone who asks, as he is whenever he mentions his possible life as an omnic before becoming enlightened/awakened. He’s obtuse around both Moira and Mercy when they ask, now you could understand Moira, considering that her “I must know how your technology functions” is kinda threatening, but why not explain to Mercy? She’s a doctor, her only interest is in helping others.
Most likely it’s actually a form of omnic/nanite tech, much like Ramattra’s abilities.
It was not said to be only advanced tech specifically but merely implied to be anything but magic. And at any rate, there are numerous potential ideas of what the dragons could be. Could be tech that’s been programmed to take on a specific shape because the Shimadas are clearly all about ~aesthetics,~ given that Hanzo stayed dressed in that old robe for how long? Could be again, the nanites thing, could be some kind of energy ability in the tattoos. There’s a bunch of different possibilities that still fall within the bounds of beliveable for the world, all more creative than “it’s magic I ain’t gotta explain 
”
Mercy’s staff is explicitly a type of science, the beam being similar (though not exact) to nanites/biotic healing, as stated by the Valkyrie short story.
Lucio’s “musical heal” is most likely related to the sonic technology that his father invented and probably kind of soundwave-based armor. Mixed with the psychological of being so upbeat.
Random magical teleportation and fox spirits do not fit anywhere within the realm of the vaguely cyberpunk/futuristic world that this was built on.
And before I read one more “but the talking hamster/gorilla-” comment: Hammond and Winston are science experiments. Literally part of a program involving gene therapy and other treatments to affect their intelligence as part of an experiment. That still works.
