Honestly, I think any broad stroke changes to ones personality as a result of ABDL would be minimal at best. I've been one for a long time and while it use to be something I was perplexed and mortified by, these feelings went away as soon as I began exploring more in my teens. I'll also echo what Trevor has said here, I think being an introvert and being an ABDL are on their own development tracks, but they often seem to coincide and have some overlap.
Much like Trevor, I think being an AB has effected my personality in more positive ways. For instance, I think being an AB is part of the reason why I am still just a big kid at heart, I'd also say it's responsible for what my friends and colleagues call my "natural calming presence", my ability to soothe things and calm a situation allowing for others to work together peaceably, I've even had friends say that having me around is like having a dog or an actual baby around, that I just chill everyone out for some reason.
Outside of those small personality traits, I'd say ABDL has had little impact on my general personality. I am smart, fun-loving, loyal, independent, a bit of an extrovert as I aim to please and like being the center of attention at parties, but a bit of an introvert as well seeing as how I often enjoy my alone time. I've had these traits since I was a child and slightly before my AB thoughts and fantasies began to emerge at the ages of 5 and 6.
Overall, I don't think being an ABDL carves out our overall personalities, consequently I think it's foolish to say that being an ABDL has zero impact on he we are as people. I guess what I am trying to say is, I think ones personality is formed by a variety of influences including but not limited to their sexual orientation, gender identity, interests, lifestyle choices, moral values, ethics, upbringing and so on and so forth. Being an AB is a part of who I am, but it alone does not define me nor has it informed the entirety of my personality.