Oddly enough, I found "being interesting" to be a skill you sort of have to try to learn and pick up. It's not like...something you're born with. You kind of actively learn how to "do the thing". I've been a wallflower most of my life, but slowly started to pick up tricks as I got older.
I found that asking other people about themselves usually kickstarts a conversation. People love to talk about themselves. Then once they reply, you see if you can find a thread or something in what they said to tug on to further the convo.
Being really into some topic or another as a hobby or profession also can give you something interesting, if you take something you know about that subject and put it in front of other people who are unfamiliar with the hobby.
Example from one of my random niche interests:
Did you guys know that honey bees aren't male/female based on having XX or XY genes? Bees that are male come from unfertilized eggs, and have only half the chromosomes the female bees have. Their chromosomes are unpaired, whereas in other animals they're paired. Basically, male bees have no father, they only have a mother.