We usually end up having the communication patterns we learned as children.
If you grew up in an unsafe environment, you might have responded by becoming passive and being quiet to stay safe, or you might have spoken up in rebellion against the environment. There is no right or wrong, or better or worse response. The adaptations are just that, adaptations you used to survive.
If you grew up in a relatively safe environment, the tendency is to take on the communication patterns of one of your parents. If you had two assertive parents, the chances are that your communication style will be assertive.
If you had aggressive or passive parents, there is a strong chance that your communication style will be either passive or aggressive. Discovering what assertive communication sounds and feels like is a journey.
Where are you sitting on the scale? I generally sit in assertive but have a tendency to flip into aggressive.