You should add maybe more cultural aspects, like giving to your characters different nationalities.
Maybe you could add a Muslim girl and boy, but even an Asiatic girl and boy
And even different sexual orientations, don’t just close all the opportunities labelling your characters as straight. They don’t have to be homosexual, they could be bisexual, pansexual,…
Nowadays our society is a melting pot of cultures, ethnicities, sexualities, believes…