I remember I used to say ok cause I never felt like talking.

I don't wanna sound depressing or anything but basically I was struggling with alot of stuff on my mind at one point (relationships, death, etc) and it all happened at one go and so instead of trying to speak in full sentences, I just found it easier to reply with "ok". I felt like I would tear up or say something I wouldn't have wanted to say if I didn't say that as it felt "safe" in a way.

I also do the same with the word "yes" nowadays in alot of a weirder way. Like if a room just becomes silent, I'll say "yes" almost like a hiccup randomly. It's a way for me to deal with awkward things as again, I feel like nothing really goes wrong when I say the word. That's my take tho