Don't make it more complicated than it is.
Influencer Marketing means you are collecting media monkey that are ranking high in the attention hierarchy of the desired target audience, then you pay these monkeys to say what you tell them to say.
That is the short version.
There is normally some diplomacy included in bartering the details and there's a lot of work and potential in the field - but i know you love short answers :)
Monkey see. Monkey do.
Pay Monkey Number 1. Every Monkey does it.