I'm still early in series but lots of themes are explored over time
The main is sibling kinship- as the main story follows brothers Owen (12) and Evan (21) who also happen to be straight and gay siblings. The brothers genuinely love each other but over the years they grew apart due to age-gap and different interests, the situation in story revives their once close bond.
Aiming for 3-4 seasons, season 1 follows the brothers but it becomes a group dynamic similar to the likes of ninja turtles, power rangers and voltron by season 2.
Maturity/Responsibility are major themes as- Owen is dependent on his parent's decisions, Evan is usually reckless.
They become carriers of a virus that mutates others into monsters, it also affects them psychologically as they unwillingly cause an outbreak. There's a Superhero/Shonen theme as they make the decision to fight off the monsters and other threats with their immunity and 'unusual symptoms' that come with their strange condition.
Sound as a tool/weapon/instigator - heavily inspired by ancient cultures who saw music/sound/vibrations as a physical/spiritual enhancer. The brothers' strange condition activate after hearing an eerie Hum broadcast across their town one night.
some of the themes hidden below because they spoiler-ish
CLICK for Other Themes
Family and Forgiveness - Without spoiling too much, their mom is another major character (with more in common with her sons).
The dad and Evan have an argument in an early episode, the extreme conditions of the outbreak causes him to rethink his perspective and also be impressed at the Man Evan has become.
Friendship, Team-work, Trust, Survival, Trial & Error, Love
are other themes that occur as they encounter other characters. Trust is a big deal as there are carriers out there with nefarious intent and many look suspicious.
Evan has feelings for another carrier named Xun who was an ex-assasin and becomes the brothers' mentor so there's a Gay/BL element
Xun manages a Gay Lounge and a few people tied to the lounge have also become carriers. The Gay lounge also acts as the heroes' base of operations.
Owen is the supportive sibling and later in story he also encounters a girl his age and has his 1st crush.
Ancient Gods/Ancient Technology vs man/modern technology- "The mythos of the story is Ancient beings had knowledge to expose themselves to specific frequencies and so became the Gods". Modern man tries a synthetic recreation which comes with it's own bag of issues.