I frequently receive a notification from my 'phone and recognize the sound as a new email on the Gmail app and many times I'm at work, etc, so I switch to my open Gmail tab. Sometimes I even wait a little bit before going to the Gmail tab. And it's not there. I usually keep my hands on the keyboard.
Checking new mail is one of the few times during the day that I have to move my hand to the mouse for a one-time action just to immediately go back to the keyboard. I got fed up because I couldn't find it on Google's list of Gmail shortcuts and started searching around. Maybe no one has ever asked the question or just no one cares.
Best Answer
The shortcut that does exactly what is asked for here is 'u', which Google labels "return to thread list," which is what it does if you're in a conversation view (i.e. a single email thread). However, if you're already looking at a list of threads (e.g. your inbox), 'u' will refresh that list.
Unlike "g, i", 'u' works to refresh any thread list you're looking at, and also does not move the cursor back to the top.
Like "g, i", the 'u' shortcut is part of the set of keyboard shortcuts that might be disabled. If that's the case, you can enable them by setting "Keyboard shortcuts on" in Gmail settings, under the "General" tab. You can also do it by pressing the '?' key in the thread or conversation view, which brings up a list of keyboard shortcuts and their meanings (although, as demonstrated here, those meanings aren't always clear). There's a link in the middle of the box allowing you to toggle whether the extended keyboard shortcuts are enabled or disabled: