In the 21st century there has been lots of progress in representation , this has been across all genres (books, TV shows, films etc). However, there is unfortunately still a lack of representation. You still see a lot of white, heterosexual, cisgender able-bodied men as main characters (or prominent characters).
Society cannot change without representation. Progress can’t be made without representation. People have these built up stereotypes of groups of people they don’t regularly see and the only way to break these stereotypes is for them to be represented in the media. But this doesn’t just mean having one character of a race/gender/sexuality/disability, it means having multiple characters of each.
Within the representation there should be a variety of characters and who aren’t defined by who they are and aren’t all stereotypes. These characters should show all the sides of a group and show the diversity within a group. Only then can people truly understand these groups. This is how people who are uneducated on issues such as race, gender, sexualities and disabilities change there mind and realise they are just people too and that they are normal.
But not only is representation needed as it helps people understand these groups it also makes members of these groups feel more validated. Lack of representation can causes self hate so representation is needed for self acceptance.
It can also make people feel happy as they can finally see themselves in fiction that they know and love (great shows are made great with good representation of groups you are in).
Ultimately representation is needed for acceptance of all kinds.