My earliest memory is of having an allergic reaction when I was about three years old. I ate a piece of Halavah for dessert at a diner and when I got in the car, my throat started itching. Soon after, my nose started running and my face started swelling. My parents then brought me to the hospital. I remember this event because it was so frightening at the time.
My personality is different now because I was only three years old then and I had none of my experiences throughout the rest of my childhood and teenage years that shape who I am today.
Your first memory is very vivid and it is probably because of all the emotion you were feeling at this time. You have probably also talked about this memory with your parents a lot, so it would be more solidified that way, since it was so eventful. I agree with you that it probably does not reflect upon your personality at all, and only remembered because of the importance of it.