As a musical theater major, musicals have taught me quite a bit. Some more literally than others, some just for fun. So if you think show tunes are just a bunch of people rapping about Alexander Hamilton (although that's brilliant)- it's not all they're good for.
The Addams Family: you can constantly be pulled in new directions (and it's okay to like it)
Little Shop of Horrors: don't feed the plants (whatever they offer you)
The Last Five Years: that inner monologue you have during auditions- you're not alone.
Bonnie and Clyde: life is short, surround yourself with people you love.
You're a Good Man Charlie Brown: philosophies can take over your life.
Chicago: men need to stop being annoying
Gentleman's Guide the Love and Murder: being a tease doesn't always get you the boy
Hairspray: everybody fangirls and dreams big
Heathers: high school sucks, for everyone.
Legally Blonde: personal accomplishment is much more satisfying than relationship accomplishments
The Drowsy Chaperone: stumbling through life with a drink in your hand is a-okay.
Rent: there are indeed 525,600 minutes in a year. Use them wisely
Spring Awakening: life's a bitch.
Wicked: don't judge someone by your first impression of them.
Aladdin: magic carpets do indeed exist.
Newies: all men need to learn to dance... like now.
Cinderella: costumes are a fucking art form.
Of course, there is much more to learn from musicals, but these are just a few of my favorites. Musicals are so much more than tunes you carry with you in your heads- so much more. And there's always new ones waiting to be discovered.