If someone is interrupting and not just trying to steal the limelight, one of several two is happening:

1. You're talking too much. Seriously, if you made your actual point ten minutes ago, it's time to stop talking.

2. They have working memory issues. Most commonly, this is related to ADHD (also, the fidgeting. Given the disproportionately high representation of ADHDers in successful startup founders, you certainly don't want to alienate this crowd by calling them "low status".)

If you're in a meeting room, provide pen and paper so they can jot down their thoughts and return to the conversation.

If you're in a video call, have a texts chat on the side where they can plant their thoughts for you to respond to when you've finished your main point.

If you're on a date, increase the frequency of turn-taking - make a short point, let them make a point, then make another point.

People with ADHD can give highly focussed attention (many become teachers, therapists and researchers) but it is exhausting. Break up workshops to allow for different attention and communication styles. (Solo work, discussions, etc.)

Re the point about being cocky and a bit of a dick, that can put you in the Hard Avoid category for many people. The trick, if you want to go down that route, is to let other people in on the joke.

If you big yourself up, flatter someone else at the same time. "Yes, TBF I was pretty awesome - but that reminds me of that award you just won! Tell me about that!"

If you're teasing someone, reveal a vulnerability of your own, or set them up for a harmless comeback of their own. "Remember that mullet you had in high school? That was hilarious. Right until I got that bad perm."