Of course it's just a word. Just. It has more than a dozen iterations listed on Dictionary.com but the use I refer to is in its most limiting sense. It came up in a movie I saw this evening. It was used a just few times, but always the same: "She's just a child… It's just a woman… It's just the wind."
Working in the service industry, years ago I had a manager that once told me to never refer to anything we served as just this or just that. Never make the customer feel guilty for not buying something pricier, such as, "Would you like a glass of wine or just some water?"
It is a word that kills magic.
To most adults, magic is just silly, just figments of our imagination, just plain stupid.
Though they'd never buy a retort like, It just is!