"Influencer" is just a buzzword. Influence itself is not a new concept. Fame is something that provides influence, and can be gained by being recognized for something and growing a following.

Sure there are new avenues to create and connect with people to gain that recognition, along with increased opportunity from a bigger population and lower costs, but how fame works and the monetization of that fame is a very old concept. There's nothing new there.

Study the principals, not the buzzwords. You can find all this in a 50 year old marketing book.