Welcome to what we know as earth. Midgard is where we live, where our ancestors lived. Humanity has evolved here for thousands of years, hunting, gathering, coming together to form large civilizations, and becoming the top of the food chain.
The creations and culture of man are seen worldwide, and their impact span across many of the continents. Unlike the other realms, Midgard has no beings capable of manipulating the elements. The lack of magical beings may be one of the reasons humanity was able to rise to domination of the world so quickly.
Beigns from other realms do occasionally make this world their home, and they will often be worshiped as Gods when they do. However, humans are quite free willed and hard to tame, thus many times they will rise against their “Gods”, and often, be successful in gaining their freedom.
Another reason for the overall lack of interest in Midgard is that the mineral resources are pretty common and useless. Because of this, humanity has been left on its own without much influence from the outside realms.
Humans themselves (as born on Midgard) are pretty useless. Very short life spans, limited strength, basic intelligence, and no magical abilities whatsoever, their purpose to other beings is small. However, a unique trait about them is that they have a soul, Firar, basically giving them an immortal conscious, even though their bodies may not be. These souls prove useful to the Aesir, whom have valkyrie collect them and transfer them into a much stronger vessel. This process turns the human souls into Einherjar, warriors of the Gods. The bodies of these warriors are much stronger than their human counterparts, and can die over and over again to be simply revived and continue fighting on. They are indeed an excellent soldier and the Aesir use them well.