"There's no sun, but so many plants and animals glow and can see!"

[conuly]

"I just don't understand why light sources and vision would evolve on a lightless planet!"

This is your problem with the setting? Once we accept a habitable planet with no sun* and no light, why wouldn't much of the native life evolve to glow and see by their glows/the glows of other organisms? Sight is an enormous selective advantage**! And once one animal can see or one plant can attract pollinators by sight, the arms race is well and truly on.

"But I don't get why the people are so dependent on light producing plants and animals! Wouldn't it make more sense for them to adapt to use their other senses?"

In ~200 years!? Exactly how fast do you think evolution works? Also, the parts of their world that don't have glowy plants are too cold to settle in, so there isn't much incentive to practice their echolocation for realsies.

* It's possible the planet is not literally sunless but simply tidally locked. Our viewpoint characters have absolutely no way to know this, or even comprehend the distinction.

** So says a member of a species that heavily relies on sight. Still....

Comments

[cellio]

Yeah, "survive in unfamiliar settings" is a common theme; if that's your concern, just give up on the genre now. Sheesh.

[conuly]

And self-evidently, the answer to "why are so many plants/animals on this planet edible" is "because otherwise this would have been a very short book".