We kinda ignore Alignment damage as a whole, allowing Divine Lance to damage to anything. I'm not a fan of Alignment as a whole so it was ripped out as soon as possible from my games.
Vorthas
I sort of go with both at the same time, I let the mechanics drive the flavor and flavor drive the mechanics. I usually come up with a concept first, then figure out the mechanics for it, and then further develop the flavor based on mechanics.
For example, my 5e pugilist character that focused on grappling and had a snake theme to her (snake tattoos and moves inspired by snakes like constrictors) was developed in PF2e as an Animal Instinct Barbarian (Snake) with Wrestler archetype for exactly the same flavor but more mechanics better suited for what I was looking for. I didn't want to go monk since the only snake-themed monk stance is more focused on Poison (Cobra Stance) which isn't what I wanted, plus she's more of a rough brawler type than mystical monk type.
https://pathbuilder2e.com/launch.html?build=456368 Here's the Pathbuilder of her. Note that due to overlapping Titan Wrestler from background and Wrestler archetype, my DM let me take Cat Fall in place of the Wrestler's Titan Wrestler, the one thing that I don't think can show up on Pathbuilder.
Basically focusing on grappling and wanting to use Suplex as much as possible.
I'm a player in an Extinction Curse AP campaign, where we are just shy of level 7, having cleared out the first level of a dungeon. So far I'm enjoying it, playing an Animal Instinct (Snake) Barbarian with Wrestler archetype (the strong-girl of the circus, even came up with my own trick where I use Athletics and the barbarian feat Bashing Charge to burst through large walls set up in the circus for entertainment).
Animal Instinct Barbarians are actually a bit tankier than normal barbarians, especially once you get the Animal Skin feat which basically ends up boosting your AC by 1 when Raging rather than reducing it by 1. They also get damage resistance to piercing and slashing damage, which is the main damage type that many monsters do by default. But yeah I can see what you mean, though I'm the health tank in my Extinction Curse party while our Champion is the AC tank, and AC tanking is usually better overall.
I'm playing an Animal Instinct (Snake in my case, Deer is probably better) Barbarian with Wrestler (Free Archetype but honestly if PFS you can just archetype into Wrestler as normal) for my grappler. It works pretty well, but yeah Monk is probably better if you really want to focus on maneuvers like grappling. Barbarian will get you higher damage than an unarmed Fighter will while Monk I think gets you more defenses and maneuverability (I could be wrong, never actually played a monk).
I heard there's an Elemental creature template for each element. Curious to know the exact details of them since it'd be relevant for the Zelda bestiary I'm making for PF2e with Fire, Ice, and Electricity monsters as templates.