I've been studying Latin by myself as a kid in middle school, and I've gotten fairly advanced with it. However, in Latin and most other languages, the present participle is/was almost never used in the place of an active. In English, this isn't the case. For some reason, it's considerably more common to announce "I'm writing," rather than "I write."
Often, I wonder exactly how the present participle came to be as ubiquitous as it is with the verb "to be," but not as a regular adjective. What is the reason for this odd choice? Why has become so frequent?