I know we use present perfect tense for past actions which have present effects. We use it for unfinished actions which started in the past and still continuing as well. I have observed that we use stative verbs like want,know to tell our unfinished positions in perfect aspect like "I have known him for 5 years." and it means I still know him,my position or state didn't change (has not changed yet) over a period of time (for 5 years).

When we want to use an action verb we started doing it in the past and we are still doing it ,we make this action stative with "be" as in " I have been working here for 2 hours ".I learned "I have worked here for 2 hours" can also be used for this sense,but it doesn't emphasize the continuity of working at least to me.

What is the origin of that why do we use "been working" and why does it imply that we are still working ? Can we consider "have been" like "have become" ? Because when we use having become something it implies that we are that thing now as in "I have become old " it conveys that I am old now. "I have become {working} " and I am still {working} now.