Centaurs are only slightly different, relatively speaking.
Shamans – Earth Shamans are better without Blood Magic, Air Shamans are better with Blood Magic, it’s clear.
Wyverns – I agree.
Cyclops – Free Cyclops are indispensable during sieges and attack a large area; Blood Cyclops have slightly better stats and are more predictable (the enemy won’t catch you off guard with an area attack on your own units; with Free Cyclops, you have to be careful, which is probably especially relevant against humans), and Blood Cyclops also have an aura. In the end, they aren’t that unbalanced.

Nah, Centaurs are quite different. The first tier has less defense and less health, and they deal weak damage in melee, which isn’t great, considering Centaurs are easily blocked. The only advantage is their questionable ranged attack, which isn’t always applicable and doesn’t always work in your favor – they can be used like Goblins to run around mines and fire traps. Plus, they have a bonus to maximum damage, which is weak compared to all the disadvantages.
Earth Daughters are almost always better, except for sieges/defending the Castle.
Cyclops might be more balanced if the ones with clubs didn’t harm their own units so much.

In my opinion, the imbalance of archers covers the imbalances of almost all other Factions (except perhaps Elves and Tier). In addition, everything I mentioned, plus Griffins. Everyone takes Royal Griffins. In general, the balance of the Order is very far from ideal.

The imbalance of archers isn’t as big as that of Elf archers and Inferno demons, and some other tiers. The bonus of crossbowmen is also strong, but it’s hard to apply, but you can sometimes play with them.
Griffins are also roughly equal; the second tier is for playing defensively, especially against melee units. The first tier will fly once, land near the enemies, and be taken down there; that’s their role. I don’t see a big difference; it all depends on the situation: what build, against whom, and so on.
Overall, I’m not saying that Humans are the most balanced; I’m just saying that they are one of the contenders, like Mages and Dwarves. But there’s no real balance between the tiers anywhere.