People First has two meanings - at least in my world there are two.
First, it's the name of a group for which I am a local advisor. It's a grass roots, civil rights organization that works hard at supporting people who have disabilities to make their voices heard, especially in the political process.
Second - and the subject of this post - it refers to the way you should speak. There is so much backlash about politically correct language that people who demand it are mocked by comedians and subjected to eye rolls from the general population. The truth is, the way you speak is a reflection of the way you think. So when you say: 'There is a disabled man' you are putting the word disabled before the fact that he is a man. Now maybe that might be the first thing you notice, but for that man and for those who know him, he may be a great juggler, or a good listener, or be a funny storyteller. For anyone that knows better, the disability is NOT what defines the man. It's typically pretty low on the list. The better way to speak is to put the person first. If you absolutely have to mention the disability, you might say, 'There is a man who has autism (or whatever).' The even better way to speak is to say, 'There's Jack.'
Also, you don't say someone IS disabled. You would say that they HAVE a disability. That way you're clear that the disability is a piece of the person, not the definition of the person.
I heard a speaker at the MACDDS conference this year. I was really moved by one of her power point slides. It said:
Be careful of your thoughts, for your thoughts become your words.
Be careful of your words, for your words become your actions.
Be careful of your actions, for your actions become your habits.
Be careful of your habits, for your habits become your character.
Be careful of your character, for your character becomes your destiny.
That was your daily lesson in both semantics and respect. Go forth and spread the gospel.