I'm trying to revise and rework one of my existing WIP stories, and I'd like someone to read even the first couple of chapters (specifically the Intro, Prologue and Chapter 1 as they kick off the whole story) and let me know a couple of things:

Is the intro too terse/choppy, or is it too long and boring? Is it even necessary, or should I let the story unfold the details as it goes along?
Are the tenses consistent?
Do the chapters draw the reader in at all and is there any recommendations for improvements?

Anyway, the chapters are relatively short if you're interested in at least reading over one or two, and I'd like to thank you in advance for any help you can give as well as apologize if it's really not your taste in stories.
Story link below:
Riven Gloom

So, right off the bat I can say that you need to work on the description. Mostly the fact that you say in the middle of it that things change, but only for the worse, and then try to cap it off by saying that your main character will also change things, possibly for the worse. Assuming you have the "for better or worse" line at the end because the MC's struggle between the light and the dark is plot relevant, take out the comment about things changing in the middle of the description, that way you get a better focus on your character and their impact on the world. Something like this is probably what you're going for:

Equestria has been consumed in fire and darkness. The land and it's people are tarnished and broken, their only salvation found in caverns deep beneath the earth's surface. But two thousand years after Equestria's destruction, a pony is born whose fate will forever change the course of the land...for better or worse.

That's just an example, but it shows how changing the middle makes the last line much stronger.

As for the story itself, first I would say to drop the intro entirely. Long chunks of exposition like that are almost never a good thing to have in a story. I know the phrase "show, don't tell" is cliche and overused, but it's exactly why that kind of exposition dump is a bad idea. Exposition isn't engaging, it doesn't get us attached to any of the characters, and in this case, it doesn't even advance the plot since it's just backstory. Instead of dumping all of that on us at once, introduce it gradually over the course of the story.

One thing you can do is to have the prologue start just before Moondrop goes into labor and give us a brief glimpse of Jack going about his day in the caverns before getting called to go to his wife, both to give us a chance to briefly see what the caverns are like, and a chance to get attached to Jack a bit before you bombard us with feels. All we need to know at the beginning is the now, the current state of the ponies of what used to be Equestria. All of the history elements in the intro chapter can be introduced over time.

And speaking of the prologue--and the first two chapters, while I'm at it--they were very good. Some of the sentences here and there could be reworded a bit just to be less awkward, but overall I don't have anything to complain about. You do a great job getting me emotionally attached to the characters, the descriptions are spot on, and the detail put into the world building is really good. It's not really my kind of story, so I'm not really planning to go past that, but if the rest of the chapters are as good as the beginning is then I'd say you've got a good story on your hands.

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I feel like everything you wrote about the intro already justified what I was feeling, I more or less just needed to hear someone else say it and confirm what I felt about it. It was written around 2-3 years ago now, and was looooong overdue for a change, and I'm likely going to cut it out completely. First things first, it will mean work on the Prologue like you said, but I'm actually all for that.

Let me ask you, as an unbiased reader, what parts of the world underground do you think I should focus on bringing into the light? I was taught to not lead readers by the nose in description, so I guess to clarify what I'm asking is what would you recommend I incorporate into the visual descriptions without getting too exposition-y again?

I'm glad that you felt the actual start of the story thus far is good, even if it's not your cup of tea so to speak. And especially for that I really appreciate you taking the time out to not only read, but leave me some awesome feedback.

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As far as visual descriptions go, the plants seem to be the most important (at least based on the current intro and the first three chapters). They're definitely the biggest difference between the caverns the ponies live in and any sort of normal cave, and they seem to be really culturally important as well. Most people know what a cave looks like, more or less, so the unusual plants that the ponies there grow would probably be the most important visual elements of the scenery.

But specifically, it seems like the way the plants glow is probably going to be one of the most important visual things to focus on. Lighting is pretty important normally, but even more so in a setting where the default is complete darkness. For example, the scene with Jack in the prologue, when he panics, has a completely different tone once we get the visual of him sitting there in the semi-dark, only lit by the dim green glow of a few plants compared to him just sitting in a normally lit room. That's just how it seemed to me in the parts that I read. Different scenes will necessarily require a different focus and all that.

But going beyond visuals, I especially liked the focus you put on the culture of the ponies in the caverns. That's another one of those things that you could put in an exposition dump, but has way more impact on the reader when we get to see it happening.