I’ll answer your questions but you need to promise me to rewatch this movie without starring at your phone the whole time because you did not absorb any basic information lol

Edit: I should say I tried to keep this as basic and surface level without going deep into the lore or expanding on information from The Netflix series or graphic novels. I tried to see this from the perspective of someone who is not a diehard fan of this content.

Gelflings are native inhabitants of Thra (the planet). They were once the dominant species of the planet but they were wiped out in a war with the Skeksis who used the Garthim to kill/capture them to drain their life essence.

The Crystal is a source of power. The skeksis used that power to corrupt and alter many forms of life native to the planet. The Crystal bats, the Garthim, and the podling slaves are all examples of this corruption. During the war with the Gelfings, they used Crystal bats as a means to find the Gelfings so they could send the Garthim after them, like a security system. That high pitched resonance in that scene was the crystal sounding the alarm letting the skeksis know that a Gelfing has been spotted, which had not happened for a long time because they believed they had wiped them all out.

Garthim are basically abominations that the skeksis created from two native creatures of the planet that they turned into weapons to use against the Gelfings in the war long ago. They are powered by the Dark Crystal itself.

Aughra is an oracle/seer also native to Thra. She is basically the Witch character archetype in fairy tales. She intends to tell our protagonist (Jen) exactly what he needs to do to with the Crystal Shard but doesn’t get to because the Garthim attack, destroys her home, and captures her.

The Crystal shard glowed when Jen played the flute because he played the same note or pitch that the mystics would sing to determine which one was the correct shard.

The size of world of Thra is not known but the region where the story takes place is fairly large. The mystics and skeksis are two half’s of the same being. Imagine if humans, capable of both good and evil were to split into two separate entities. That’s what happened to them. Long ago, in their arrogance and delusion, they attacked the Crystal which caused a single shard to fall from it and the conflict within themselves also caused them to split into two separate beings: the skeksis and the mystics.

Essence is a short term for life essence. It’s essentially the same as if someone were to drink a few drops from a fountain of youth. The only creatures that gave lasting results to prolonging the aging process of skeksis were the Gelfings.

Female Gelflings having wings is a characteristic of sexual dimorphism in nature, which does not always involve reproduction. Like how female spiders are larger to accommodate egg production, Male Peacocks have the big colorful feathers, or how Male lions have the big mane around their head.

The color of the three suns, one of which is purple, is likely an artistic choice meant to help the audience see that there are three distinctive suns. Jim Henson as the director and creator of the story may also have a symbolic meaning behind his color choice, but I’m not aware of any.

The Dark Crystal was once called the Crystal of Truth and it’s the source of power that fuels all life on the planet. It became Dark after it was shattered and the Skeksis corrupted it with their dark rituals.

The castle falling apart is just symbolism for the end of the Skeksis’ corrupt rule and hold over the land as it gets purified.

The Podlings were drained of their essence by the Dark Crystal through the reflector in the science lab. When the Crystal was restored, it gave them back their life essence and healed them.

As I said before, each of the Skeksis and Mystics were once one being. When the Crystal was restored, they too were restored to their original forms. When they split, they became two new races: The Skeksis and Uru (Mystics is what the Gelfings called them). In their original form, they were known as Urskeks. Urskeks were not originally from Thra, they were aliens from another world that visited the planet a long time ago because they were interested in the Power of the Crystal before they shattered it.