Humans are a species in the world of Undertale and Glitchtale. Compared to monsters, human souls are superior due to the permanent presence of DETERMINATION (and can vary from the strength of the soul) on it, but Monster souls don't have determination (Excluding Undyne in her Undying form.) Each human soul is different and can be divided in different soul traits.
Humans are made of flesh and are nearly all the same (the skin color, the gender, the height, the size, etc. can change) but between them, they are unique because of the different type of personality (related to their soul). Humans are physically superior to monsters.
Appearance of Soul
Humans souls are in the shape of hearts, Their color can vary from one person to another as their trait from the colors: Red, Orange, Yellow, Green, Aqua, Blue, and Purple; or in their former names Determination, Bravery, Justice, Kindness, Patience, Integrity, and Perseverance. Also, it is one of the humans' weakness: if a human is killed by a monster, the soul of the human can persist, which allows the monster to have the time to absorb it.
Powers and Abilities
Magic : A select amount of humans posses this ability, and uses it in many purposes (war, healing, etc)
Strength : Humans can be physically stronger than monsters
Weapon summoning : Like Frisk, humans who have been trained in using magic has the ability to create physical weapons using magic and use them in combat.
Enchantements : Humans who aren't able to create a physical weapon out of their magic can enchant an item they choose as their weapon.  A perfect example would be the Real Knife
Humans can't absorb other humans souls.
Humans can train to make their magic more stronger in order to be able to form their own weapon. 
Humans with brown or any normal color eyes just don't have powers. 
There are people out their who have no magic powers because they don't have affinity with magic.