When I create something in the past and do not mention the time, the first thing that comes to my mind is: Present Prefect (PP)
I'd use the PP to describe an action when the time is not important and an action incomplete , unlike Simple Past to describe when something happened and an action completed.
I found this sentence on Wikipedia and the author used the Simple Past. I'd use Present Perfect but it always confused me.
Doctor Manhattan was created by writer Alan Moore with artist Dave Gibbons.
Doctor Manhattan has been created by writer Alan Moore with artist Dave Gibbons.