I do think that "some" of that can be learned with proper support provided by people/mentors who actually understand the issues. Obviously, some people genuinely don't have the ability, but a lot of it is the poor way that we don't support or train people to do it.
So much damage is caused by teachers at schools who just "don't get it" that some people are introverted, nervous, anxious, etc., about public speaking etc, and who think that making them "just do it", will cure them, but instead make them worse.
I would deliberately stay quiet and look a fool rather than even answer questions in class for fear of saying something stupid, and many teachers would make it worse by opening shaming me in front of class mates for "not knowing" a simple question. Bad enough for other kids to laugh, but teachers doing it too is unforgivable. Same with having to do class presentations - I did a few, made a mess of them, and subsequently just bunked off school for future ones! That kind of thing stays with you throughout your life.
In my career, there were times when I had to give presentations, etc., which literally made me ill just thinking about doing it, causing sleepless nights, causing physical sickness beforehand, etc., all from childhood memories and the fear of looking stupid. Thanks useless teachers for that!! I somehow got through it but never felt comfortable, and I knew that my performance/presentation was woeful, not through lack of preparation/planning, etc., but sheer useless delivery due to being overwhelmed by being on the spot.
And no, it doesn't get easier the more often you do it! If anything it gets worse because you become obsessed with past failures that you can't get over it, and foul up the future ones too!
I've personally been very upset when I see other people suffer the same, especially in work environments, when sometimes they're visibly struggling, shaking, etc., but of course, they've got to do it because everyone else has to do it and there's still some weirdos out there who think that you can overcome the anxiety etc just by doing it! I certainly made sure that none of the staff in my department had to suffer in the same way when I was managing my dept, and I always ensured some proper training/practising etc was available for the few times when presentations etc were essential, but mostly, I pared down the number of presentations required and dramatically reduced the size of the audience etc which I always found to be helpful working in smaller familiar groups.