Gryffindor is described as a brave and fearless college. Its symbol is a lion, and its colors are red and gold, which shows this very clearly. Its founder is Godric Gryffindor. Its element is fire, and its ghost is almost headless Nick. Gryffindor students are usually very brave and chivalrous, but they can also be reckless or arrogant.
Famous members are Harry Potter, Ron Weasley, hermione granger and albus dumbledore. In the Harry Potter series, they are regarded as major colleges, and almost every major figure is assigned to them, probably to expand the competition with Voldemort's Slytherin Academy. It may also symbolize the importance of bravery in wartime and the strength of loyalty to the opposing knight, which Gryffindor students often have.
Ravenclaw is described as the home of the wise. Their badge is eagle, and the colors are blue and bronze. The founder is rowena ravenclaw, and its element is air. Ravenclaw Ghost is the daughter of Ms. rowena ravenclaw Gray, namely Helena Ravenclaw. Ravenclaw's students are smart and studious, but they may be regarded as "eccentric" and sometimes they are very competitive in exams.
Famous members include luna lovegood, Filioud de Flitwick and Zhang Qiu. Ravenclaw's ghost, Lady Gray, is famous for helping Harry find Ravenclaw's crown. Her story may reflect the themes of power, betrayal, jealousy and pride. In a member like luna lovegood, Ravenclaw may be interpreted as that everything has knowledge, even though knowledge may not exist at all, or it seems impossible to believe.
Hufflepuff is called the home of loyalty and fairness. The mascots are badgers-yellow and black. The founder is helga hufflepuff, and the earth is their element. Hufflepuff's ghost is the fat monk. Hufflepuff students are considered loyal, have a good sense of fairness, diligence and kindness. But they are looked down upon by others, considered unsuitable for the other three, or considered "weak" or "without talent". Famous members include cedric diggory, nymphadora tonks and Newton Scarmand. Hufflepuff may be used to show people how society treats other unsociable people unfairly. Hufflepuff may say that these so-called "weirdos" are deeper and have their own interests, skills and talents.
Slytherin was described as an ambitious and cunning college. Their patterns are snakes and their colors are green and silver. Its founder is salazar slytherin, and their element is water. Slytherin's ghost is the bloody baron. As we all know, Slytherin is ambitious, eager for power and inclined to purity.
They are considered to be the "worst houses" in the play, producing the darkest wizards and witches. They are portrayed as the least popular of the four families. Famous members are tom riddle (Voldemort), Draco Malfoy and severus snape. They are regarded as "black houses" in the book and are symbols of evil. However, not everyone in Slytherin is dark, which may mean that the concept of good and evil is not simple, especially in Professor Snape. This sentence may be used to show that even a college like Slytherin, or other similar situations in real life, is not necessarily "bad".
Please note that these are just my explanations of what each house may try to express, just as you ask their roles and what each house stands for. Of course, they may not mean anything, so this is just my opinion.