Speaking of shyness, I used to be quite shy and I still consider myself an introvert. (Introverts "recharge" when they're alone, while extroverts "recharge" whenever they get to be around people.)
But I'm not "shy" anymore, probably because I've had so much experience starting up conversations and talking to people.
When you have more confidence about yourself (who you are, what you're good at, what you do for a living, etc.) that tends to make socializing much easier. It also gives you a good starting point for conversation.
I think socializing was hardest when I didn't know much about myself, there was nothing about me that was very special, and I didn't have anything to distinguish me from all the other guys. And in fact, I was majorly deficient compared to my peers in many categories (e.g., sports, physical height, etc.)
Let's put it this way -- once you've enriched your own life by learning many skills, getting lots of experiences, it's so much easier to socialize because whatever a group is talking about, you can join in. Are they talking about farm animals? Mowers and tractors? Anything involving working outside? Computers? Smartphones? any topic related to the Catholic Faith? Cooking? Survivalism? Gardening? Different parts of the USA? Homeschooling? Child discipline and raising? Science? History? Pre-history? Languages? For these and several dozen other subjects, I can join in.
This wasn't true at all when I was 17, unless someone wanted to talk about "Final Fantasy II" for SNES.
But these days, there are few topics that I am forced to sit out on: sports, fashion trends, and modern TV shows (and most movies).
But knowing how to do thousands of things also gives you confidence. And since these abilities are all old-hat for you, you don't necessarily become vain about it. (If you're vain, that's a separate, unrelated issue.)
It's hard to act like a confident man when you still feel like a boy -- and for good reason! A man should know how to change a tire, and in general take care of himself without any problems if "mom" weren't around to take care of him. So a young man who knows deep down that he still depends on his mother for many things is going to lack confidence. It's hard to fool oneself.
I guess the moral of the story is: make yourself a Renaissance man, or pretend you're competing for "Most Interesting Man", and you'll never be bored.