Why is "community" taking over the place? Is this a usual phenomenon here? A bug?
When the site is not very active the software powering this website will automatically bump a question that does not have an answer selected as correct so it can get more attention particularly from newer members. This activity will be shown as being done by the member "community" who handles special cases such as this. With this being a holiday weekend in the US it is particularly slow so most of the activity around here is bumped questions as displayed in that screenshot.
Here's the stackoverflow FAQ question/answer on this user.
I looked into and it does look like a bug of some kind. Some of the questions with the Community user marked as the last editor have been migrated from another site. I could see Community being appropriate for those questions. However, I am completely unsure of the other questions marked as last edited by Community.