Major Plothole

The starfighters were recruited from many worlds because they had the "gift". The gift is so rare that there were only that handful of beings who qualified. They weren't natives of Rylos, so they didn't have the same life cycle of the "people" from Rylos. They were as alien to Rylos as Alex was, even though they seemed to take their recruitment better or were recruited earlier, as shown by the uniforms they were already wearing as well as their easier adoption of the "victory or death" chant started by the ambassador (I think that's what he chanted).

I get the sense that you're saying Rylosians don't die like humans die because of a couple scenes. The first is when Grig says death is a primitive notion and that Alex should think that the other starfighters have passed into another dimension. This seems more like a throwaway line about alien notions of spirituality than a statement about the potential of those blown up starfighters to return to our dimension. For all intents & purposes of the inhabitants of our dimension, those starfighters are dead & not coming back.

The other scene is where Centauri seemingly comes back from the dead, but then reveals that he didn't die, he went into hibernation so that his body could repair itself. Perhaps if the laser gun wound that Centauri received was more than the "stratch" that Centauri downplayed, his body wouldn't have been able to repair itself & he would've died. Anyhow, when he takes off his human disguise, Centauri is revealed to be of a different species than the Rylosians. Centauri looks like one of those Trade Federation aliens from the Star Wars prequels (remember the ones whose way of speaking was accused of being a racist representation of Asians?), while the Rylosians look mostly human except that all of them, male & female, seem to have male pattern baldness. The other starfighters are a bunch of different species so they probably don't have Centauri's regenerative power. Even if they did, it's doubtful they could regenerate themselves after being blown up.

Regarding the gunstars, perhaps the great betrayal by the Ambassador's son Xur had an adverse effect on Rylos' economy or means of production. If Xur was able to break down the frontier shield, maybe he was also able to break down the manufacturing of gunstars? This guess is probably off because the movie seems to suggest that those without the gift aren't worthy of operating a gunstar, so why make more gunstars than they have starfighters for? It's not a plot hole, but it is a major stretch to think that being able to control a couple joysticks to put the crosshairs on enemy spacecraft is such a rare skill.

I can live w/ these stretches and I like the (admittedly cheesy) movie, but the part that bothered me the most was the climax: the secret weapon of Alex' prototype gunstar. It didn't require the "gift" to press the button that made the gunstar spin rapidly & shoot everything in its parameter. Alex was just along for the ride at that point. This special weapon destroyed more enemies than did Alex' conventional skill of aiming & shooting the regular weapons. A more realistic "last resort" weapon that would've destroyed all of those enemies in range would've been a large bomb, but w/ Alex, Grig, & the prototype blown up, there wouldn't have been the Hollywood ending.

If they're alive, they aren't alive in our universe. Remember, Grig said he prefers to think of them as fighting evil in another dimension. And really, I think that was just another way of describing the afterlife. Centauri is the only alien we see come back from the dead, and that was probably just something his species is capable of, not a trait that all Rylians and Starfighters share.

Centauri wasn't a Rylan. The Rylans are the mostly-bald people who were the bulk of personnel at Starfighter Command. And there's a big difference between having an abdominal wound and being basically blasted to stardust. For instance, an earthworm can regrow itself if you slice it in half. Throw it in a campfire and it's literally toast.

Not a plot hole at all.

amazing movie, but

why not just teach others to fly? i mean it didnt seem that hard to fly