Human (-ish)

Features

Diseases

Due to the natures of magical coherency/ownership and souls in general, life tends towards being larger. Bigger organisms (generally) have stronger magical claims, and therefore are harder to affect by smaller foreign bodies. This means that in general, diseases have far more trouble spreading than in a world without magic. Most bacteria and viruses exist below the magical coherency limit, thereby having no magical claim.
Auto-immune diseases and such still exist as frequently as otherwise, but transmissible sicknesses such as inflections or flu are extremely rare. The concept of a plague didn't exist for millennia until a certain mad Terian emperor decided to create one, specially magically engineered in a way that evolution would never reach ordinarily.
Larger parasites, on the other hand, are more common.

Eyes

Eyes being windows to the soul are more than just a saying in this world. As a result, most people's eyes are actually faintly luminescent, the exact color being based on their natural hard light. Occasionally, small flecks of the light color can be seen within the eye. This acts as a tint to their biological eye color, generally more visible with lighter eye colors and low-light conditions. The intensity of the color is based on the person's soul flow. Natural flow typically varies from ~25%-300% of baseline, resulting in a great variation of intensity even among non-mages. In powerful mages, the luminescence can be great enough to act as a light source on its own.
The common Cotd pure black eyes hide this effect. The white eyes dampen it simply because they are white due to being cloudy, and the red eyes act as any other. Most 'red-eye' Cotd visually have other eye colors due to soul flow (though the underlying red tint limits the breadth of possible colors).
Midlanders, with their wariness of arcane magic, often naturally select against the people with the weird glowing eyes, resulting in a decreasing average soul flow within the population over time. Northerners are the opposite, with their love of magic.
Compared to a control group with neutral feelings towards arcane magic and no heavy adaptations (desert nomads), Midlanders have an average of 50% less flow rate, northerners 30% more.
An interesting consequence of this is that it's technically impossible to be in true pitch darkness: since one's eyes will always emit (not just reflect) light, one can't really be in total darkness. Magical darkness is seen as all the more unnatural as a result, since the negative light effect can create the visual effect of true darkness in a way that a mundane pitch-black room never could.

Inheritance

Planar affinity is almost completely inhereted from the mother. See also Elemental Affinity (in humans).
As a general rule, any significant deviation from baseline human will be inherited primarily from the mother's side. Female ghouls have ghoul children regardless of the father etc.

Affinity Mixing and a Celestial Quirk

This is something interesting to remember: barring exceptional circumstances, affinity is maybe 95% inherited from the mother. As a result, bloodlines can only theoretically have multiple affinities matrilineally. However, for unknown reasons, anyone born with multiple affinities is always male. While individuals can gain multiple affinities through rituals and such, or through inheriting from their parents, it stops at a single generation every time. This is such a niche law of reality that most people can't even hope to recognize the pattern, let alone try to figure out its underlying cause.