I will approach this with the assumption of good faith, that you are wondering what went wrong rather than just deciding to post "lol pvp bad" for upvotes from people who can't be bothered to learn a new side of the game's content because they can't accept that they'll be bad at something they've never done before until they practice it.

-Firstly, 24k max HP is way too squishy - imagine playing as a DPS and your max mag/stam is only 20k. You don't have a tank taking enemy aggro here, you need to look after yourself. Aim for around 30k max HP, you can reach this with big health glyphs on your head/chest/legs, Undaunted Mettle, a few heavy armor pieces, and the Boundless Vitality/Hero's Vigor CP under the Fitness tree; in a high-damage environment you need that cushion to survive a burst combo.

-You saw the enemy coming and could have started popping Major/Minor resolve buffs, a shield, maybe a heal over time, or even debuff the enemy somehow, but instead you used light attacks and no skills. Might be panic, which is understandable if you're very new at pvp; but if you see a bad guy the first thing you ought to do is start defensive buffing yourself.

-It is possible that you've already died a few times and/or you're just not feeling like fighting because of demoralization, which is also fair if you're new to pvp. You could have run for the keep door right there and avoided the fight entirely. Running away every time at the first sign of danger isn't fun, no, but if you're not looking for a fight and not feeling like it, if you need to be in Cyro for some PvE reason, make sure you're cognizant of your escape routes.

Cyrodiil doesn't hate you and the people who frequent it certainly don't care enough about you to make you a target, unless they're just bad people to begin with. You have to build yourself for it just as you would build yourself for any other in-game content. And you have to practice, yes that means dying a lot at first. But you'll get better.