Hi Alay,
You asked: Is there any explanation for our physical characteristics (even in the human plane) – i.e some are born with pleasing features and some are not. Even in the animal plane, some have pleasing features while others have fearsome features.
The differences in people are all based on their kamma. The physical characteristics, beauty, health, wealth all of this is based on previous kamma. These differences can be seen in the animal, human and even in some lower deva realms.