Starting with the release of tvOS 10.1 and the launch of the new TV app for Apple TV, the behavior of the Home button (the one looking like a TV icon) has changed. Prior to this update, pressing the Home button would take you back to the main Home screen. But after the tvOS 10.1 update, pressing the Home button takes you to the new TV app.
This can bring some confusion or downright frustration, especially if you’re not planning on using the new TV app. Fortunately, as someone pointed out to me, there is an easy way to remap the Home button so it takes you to the main screen again instead of launching the TV app.