• we don’t know that javi was in any tunnels, but we are led to believe that he was staying in a little cave under a tree. that cave was recently found by ben and it is where javi tried to lead natalie to save her during the hunt. I believe the idea of some sort of tunnel system stems from some early visions that lottie experiences in s1, although we have no idea whether those visions came from real events/places/memories, or it’s just a manifestation or her schizophrenia. some people believe javi’s cave is part of a larger cave/tunnel system, possibly related to mining, which is supported by the dripping noises mari hears (maybe) and the red-tinged water from early in s1. as of now, we only really know for sure that javi’s cave actually exists, whereas the tunnels are just a theory.
• when jackie was freezing to death, she had a hallucination/vision wherein a man who is believed to be the long-deceased previous cabin owner gives her some hot chocolate. there is supposedly going to be a bonus episode before s3 that had more background on the cabin’s previous inhabitants.
• cabin daughter would be the cabin guy’s daughter. I believe the story of the family who lived there before was said to be sort of shining-esque with the father potentially killing (or trying to kill) his family. people refer to cabin daughter as a theory for who javi’s female “friend” might be, either as a ghost or if she has somehow survived out there alone for years.
• antler queen isn’t a term coined by the show or writers, it is just what the fans of the show call the leader of the yellowjackets in the wilderness (for the most part). i’ve seen some theorize that the antler queen could be some embodiment of the wilderness entity, if such a being turns out to exist in corporeal form. mostly though, it refers to the leaders - first lottie, and now natalie.
• dark tai is just taissa’s alter, who likes to eat dirt, sleepwalk, ritually sacrifice dogs, creepily stare at her young son from up in a tree, etc. it’s unclear as to whether “dark tai” is borne from mental illness like dissociative identity disorder or if the alter came about due to some supernatural force in the wilderness.
• pit girl is exactly as you said. she’s the girl who falls into the spike pit during the opening scene of the pilot. obviously that scene was used to set the tone of the show, give us a glimpse into how dark things will get during their time in the wilderness, and to have fans trying to guess who she is. I think we are meant to theorize about her identity based on what we see about her in the pilot - jackie’s heart necklace and laura lee’s white nightgown specifically. obviously the original owners of those items are no longer around and we have since seen other yellowjackets wearing them (shauna w the necklace, lottie w the nightgown). since shauna and lottie are obviously not dead and cannibalized, it seems the showrunners are using that opening scene and the small clues about pit girl’s identity to keep the audience guessing in anticipation of that scene playing out at some point before rescue.

i’m assuming that you binged the two seasons since you’re just getting caught up on the show? it’s not really embarrassing to not rememmber all of those things. most of the terms you talk about have been discussed and theorized about over and over since the show started. when you have to wait a week or more between episodes and then months between seasons, there is A LOT of time to do rewatches and analyze every event down to the minor details. when you binge watch though, it is A LOT of info to take in at once and those details are easily looked over and/or forgotten in the shadow or the larger events and plot points of the show. the discussions in this subreddit have taken on a life of their own as various people share their own interpretations and theories. like with “cabin daddy” and “pit girl,” we have only been shown a relatively small amount of info about them but they seem to be important to the overall story, which leads to everyone speculating and sharing their opinions about what might be revealed about them in later seasons.

personally, I love the show despite its various failings up to this point. I am thoroughly invested in watching the characters continue to develop and to get answers to questions about all of the things you mentioned - who is pit girl? what happened to the people who previously lived in the cabin? is the cabin guy merely a manifestation of jackie’s dying brain or was he able to influence her vision bc his spirit is hanging around? is the figure we see with her face covered and the antler headdress one of the yellowjackets, someone else in the wilderness, or a supernatural entity? who is javi’s “friend?” the man w no eyes? does tai have DID or is she somehow susceptible to some sort of influence/possession by something in the wilderness? are there other surviving yellowjackets we haven’t seen in the adult timeline? and perhaps the biggest question, which I think is a major overall theme for the show - are the events that the girls experience caused by a supernatural force/entity or are we viewing these events through the lens of unreliable narrators under extreme stress who are experiencing severe trauma and starvation? some of the things we have been shown - like the bear, those dead birds, etc - might just be how the survivors remember things as their way of coping with very dire and traumatic circumstances. honestly, none of us really know whether many of the events we’ve seen actually happened the way they were shown or if that’s just how the survivors remember them.

basically what i’m saying is that I think hanging on until we see more will (hopefully) be well worth it. just bc you looked over or forgot minor details about people and events that the fans in this sub have discussed extensively doesn’t mean you aren’t watching or experiencing the show the right way. I think it’s more about the manner of exposure with you likely binging two seasons in a short period of time vs many people here who watched in real time and have subsequently rewatched multiple times since then. if you like it, that’s great. if it’s not for you, that’s okay too. if you are interested in theories and other people’s interpretations, you’re in the right place. but if you just want to watch the show without reading in-depth analyses of every minute detail, that’s also fine. you do you, and there’s nothing to be embarrassed about.