I agree with the nature of your comment, but I would like to make a small tweak to it: instead of presenting people as "naturally" being introverted or extroverted, I would like to posit that the extroverts you refer to are just more experienced in these kinds of social interactions.

I'm kind of weird because a lot of people see me as being extroverted because I tend to act that way when I'm comfortable with a person. But I'm also the type to magnet to the sole person I know at a party and only occasionally talk to their friends if they speak to me. At the last big social event I went to I probably spent as much time talking to people as I did walking around aimlessly trying to appear busy because I was too afraid to talk to someone new. I don't drink but I can understand why "liquid courage" is so common at socials.

The thing is that we tend to assume if we see a so-called extrovert that they must also not face our same inhibitions. But I have not observed this to be the case. Even people so extroverted they still are in touch with strangers they met abroad on a train (in the time before the internet, no less) share in my feelings of social awkwardness. Conversely, I know people who are much more meek and mild than I who completely excel in a social setting. In both cases, they said the edge they had over me was just experience.

If you think yourself an introvert, think actually about how many times you've tried to talk to people at socials. If you're like me at the last social I went to, then you're getting so much less practice than the guy having twenty awkward conversations.

At least in my case, I am least practiced when it comes to introducing myself to a group of strangers. But I am convinced there is a right combination of words and actions that you have to get a feel for. I needed to ask someone I didn't know a question and a friend of mine went with me; he exchanged a few words that I don't even remember and suddenly I was enough into the conversation that I could get my question out without feeling completely red-faced.

I don't know if you practice presenting slideshows like I do, but when I first practice, I'll do a bunch of 30-second false starts when I present a new slide. I'll start to say something and it will come out wrong or I'll work my way into a corner and get stuck, then I'll restart. Eventually I figure out the right formula for introducing the slide, and the rest usually follows from there.

How you practice socializing is still an open question to me. I know I make it sound easy, but I still have trouble overcoming my fears. Even if I intuitively know the right moves, I lack the confidence to make them. Perhaps my biggest issue is that for a long time I did not approach being social as a learned skill, so I didn't put myself out there. I do believe that with experience most anyone can be the life of the party.

Oof, this ended up being a bunch of words. Whoops.

Edit: one additional thought fragment. Part of what drives my social anxiety is a desire to be accepted by others. For presenting, perhaps this is a strength: I will meticulously choose my words assuming my audience is adversarial and I need to win over their attention and adoration. For socializing, I think it is often more a weakness. Caring so much about presenting myself well ironically causes me to never want to put myself out there because, well, I know I'll be awkward. I still have yet to convince myself emotionally (though I know it logically) that most people I meet will have forgotten me by the end of the event - or they will at least have forgotten the several gaffes I made that keep me up at night.