Traditionally,first we become human, then we are (fully) human, and, indeed, conceptions such as childhood and human rights are derived from this premise.
However, the premise is unsound. Childhood is a time of being as well as becoming, and adulthood a time of change as well as stability. Children have relatively fixed identities while adults are relatively insecure in theirs. Indeed, social theory indicates that some of the traditional characteristics of adulthood, such as the settled career and the fixity of judgment and preferences, have become ever less stable in the late modern or postmodern age. Adults are not even more skilled than children in every respect: for example, in terms of general computer literacy. Aristotle’s views on the matter remain highly influential but are by no means the last word. At whatever stage in life, human being is human becoming, though not always human improvement.