I had two rambunctious big brothers running around and keeping my parents well occupied. They were only a year apart in age, 4 and 5 years older than me, and their sibling rivalry was off the charts. So, by the time I came along, neither the baby-W2R nor my first words were quite the center of attention. I don't think anybody heard them, to tell you the truth!
When they were both on the high school football team together and at after-school practice I think I was first able to get a word in edgewise....
My daughter, on the other hand, was an only child. Her first word was "Da-da-da-da-da-da-da-da-da-da-da-da-da [...]" ad infinitum, which supposedly was "Daddy", or at least her father thought so. I had my doubts. Another early word was "Fa-Fly", which meant either "butterfly" or "French fries", depending on context.