Wow! First things first: the length of your comment shows your passion for the subject, so how could I possibly be offended by your critique? ;) I might disagree with certain points, but I take no offense. I might not even disagree. My design goals might simply be out of alignment with your tastes.
It's all good! My wife is also neurodivergent. I think I understand when you are talking about processing RPGs a bit differently, but correct me if I'm wrong
I think I'm seeing 3 basic critiques/concerns here, right?
1. Moving from classless Talents to character classes with Templates
2. The need to take Templates in order when not every Template fits your vision for the character
3a. Species as class is interesting, but not all fantasy heritages are represented in Relic
3b. My interpretation of what makes a Dwarf the "dwarfiest" dwarf there is, is not going to align with other people's ideas about what the ur-Dwarf should be
I think that #1 and #2 can be addressed together. It comes down to that fundamental rule of DMing: your home game is unique to you. Ignore or change anything you like. :)
If I wanted to make Relic more like Glaive what I would do is this:
1 & 2. Treat class Templates as themes, the way Tallents are treated in Glaive. "Here are some things that are typical of Barbarians, but anyone may select them."
That's actually how Relic multi-classing works already, except that you need to take the Templates in order. So get rid of that rule too.
While I tried to create logical progressions for the class Templates, they are not particularly well balanced or play-tested in most cases. It was just what made sense to me based on my experience playing other RPGs.
You can even work around what feels like it should be an exception to this rule: Species as Class. If my human wants to pick a Dwarf template at level 3 I would just say they were adopted into the culture, underwent weeks or months of ritualistic training to gain the Iron Gut ability, were taught the secrets of sonic throat singing, and had gems embedded in their temples or eyes so that they could gain Stone Sight.
Something like this would be a big deal though and I'd want to tie it into a whole adventure somehow.
Also, wow, making a deal with a devil and becoming a Tiefling mid-game sounds like another awesome adventure hook.
3A & 3B. I think any DM, should feel free to reinterpret, edit, or ignore what I think makes interesting templates for different heritages. If you think Dragonborn should have warm amber eyes that glow subtly with their inner fire and not the cold dead eyes of a predator, I cannot argue with that. :) If you don't like The Stare as an ability you can replace it with something else and it's unlikely to mess up your game.
As for heritages that are not represented: This one is on you to work out. I might eventually publish some more, but my "to-do" list is already quite long, so it will be a while.
I can give you some advice on how to do it though. I tried to make each species Template equivalent to class templates. My goal was that a human PC with 4 Temples of Thief was not any better or worse than a Tiefling PC with 2 Tiefling Templates and 2 Thief Templates. Just different in interesting ways.
Some heritages come with enough lore for a full 4 templates (Dwarf, Elf) while others are newer and less well described in fiction and RPGs (Dragonborn, Tiefling). This is, of course, just my opinion. You might easily be able to write 4 templates of Dragonborn.
What determines the number of Species-as-Class templates for me is how different they are from baseline humans.
A Tortle looks very different. But I think the only mechanical differences in D& are the natural armor from the shell, claws (that do the same damage as fists I think?), and the ability to hold their breath. I could write that up in a single template.
Now my essay is matching and exceeding your essay, haha. I will end this here. I hope I was able to address your concerns. Let me know if I did not.
And I would be happy to offer feedback on any addition heritages that you might feel inspired to write up!