The default Android file manager is a serviceable app. It does what you need and not much more. Plus, like all built-in Android apps, it plays well with the operating system and has a consistent look ...
Are you trying to transfer files from your Android device to a Windows computer? This is not something most of us do very commonly, but when it’s needed, trying to figure out how to transfer files ...
That said, if you do manage files on your Android phone, you'll quickly realize that most Android file managers are quite limited in functionality. Open source software may not always be the best ...