Dude can I be honest with you for a second. Look at the team composition. No one on your team could protect Jynx from Pantheon. Literally, every single time he attacked her, I'm sure it was a death. Maybe her positioning was bad late game, but early and especially post 6, he would feed on her easily, and then be unstoppable from then on (as a typical feast or famine)
Jynx and Annie make a strong "burst" combo, and can slow or delay enemy approach, but with Panth dive and ulti, he would kill jynx as soon as he lands on her, even if annie does have ulti up.
I have to ask, please don't take it personally, but were you first pick? I ask because it looks like you were Zed mid. Which meant that annie filled the AP role, so jynx didn't have peel from a champ like Thresh, braum or even leona. Annie support is not helpful if the enemy can control engages (like with Panth) and I am assuming he realised this early hence why he focussed her so hard. Zed also is not effective at stopping Panth, just as champ match up, nothing to do with you. Meaning Darius or Xin needed to be peeling for Jynx HARD, but my guess is that Xin was going in on enemy adc while Panth 100-0 Jynx, then cause he is fed, he would kill xin too, and since Annie is behind, she doesn't have the magic damage to burst him. Darius was your only hope to stop Panth, but at this point, I'm guessing he wasn't in any fights until Jynx was already 10 kills down.
I've seen this a lot with Pantheon, feast or famine, if he gets ahead he is very oppressive, and your team composition lacked the ability to stop it. If Annie warded well, the two of them played defensively, he would not have gotten ahead like that, if she was a tank with a more reliable stun, she could peel better, especially if he was already ahead from winning top lane. From just the team composition alone, I could deduce that Annie was the weak link, not as a player, but as a champ, so naming and shaming Jynx like that is unfair for those that don't look closer. And if Annie was forced to pick AP support because of an AD mid, then you really shouldn't rage like this. (especially the naming and shaming part). But that's IF she was forced AP support, I don't know any AP top that could defeat Panth, so my next assertion would be to look at Xin.
If he babysat top, Panth would get destroyed, it's also the easiest lane for him to gank based on champ types, he also might have been able to pressure lux to stop her roaming bot for more free kills. Because he chose an Ad assassin (when you had an AD assassin already) your team compo was f*&^%d so whoever picked second between you and Xin set your team behind. If you picked Zed first, he should have gone fiddle or even Cho or Dianna. Annie should have gone Braum who is really hard on Sivir and can reposition well to counter Alister's play style (which is a disaster for Annie) And panth would never have gotten ahead like that.
I don't think Darius could have done differently, and I honestly can't see a world where Jynx would have won that game, if she was anything below plat 1. I personally am against first pick Zed's and my bias might show, but games like that happen most for me when the team badly compensate for an AD mid first pick. But it's not your fault if you picked first, I'd say it's Xins or Annie, one of them should have picked different (especially Xin, Annie may have been forced AP, but Xin had options). But if Xin picked before you, you certainly should not have gone zed, because that was suicidal for team composition, even Yasuo would have been better due to synergy. If annie picked first, then really nothing could be done, just counter picked, but it still comes down to Xin.
Based on those scenarios, Xin is most likely at fault in that game, then Annie, then maybe you, in that order, Jynx needs peel, no one on your team was in a situation to do that, this is a team game, look at the team, not just the adc who got focussed, it's not like adc's are usually focussed right?
Note: for clarity, Darius could peel for Jynx, but wouldn't be able to until mid/late game, when she was already too far behind. Xin could peel for Jynx, but based on score was probably engaging, or following Annie's plays. Anni can't peel too well, she is kind of a one trick pony in that situation, if she used Ultimate to engage, and Xin went in (late game with Zed as well, with only Darius left to peel, except he is your team front liner, so Jynx would be solo) Panth or Lux could focus Jynx for free kill, while Alister perfectly peels for Sivir every time
So early game, Annie engages, Alister is too tanky and Sivir has spell shield, they attack Jynx who now has no peel. Annie doesn't engage, she has to wait out spell shield before she can stop Sivir, and lux, lee or Panth (or all) gank bot, Jynx can't do anything
late game, Darius is at front as tank. Xin, Annie and Zed all engage types, who peeled for jynx?
Team composition is a big deal, especially in soloQ where communication is not being used to make up for bad compositions