We're pushing Whitespace Neko on Tumblr at the moment. It's Neko with his tie and cigarette making snarky observations about life directly to the camera. Panels are stacked vertically so it's easy to read on phones, and it updates every day.
Also I've been having fun on Tumblr sharing gifs and whatnot, so check it out.
I think the main thing I've gotten out of Tumblr is I started watching Steven Universe, which starts out cute and funny and then goes down a tremendous rabbit hole of characterisation and science fiction weirdness as it explores just how truly Alien the alien characters are. There's about 70 episodes so far - most of them are ten minutes long but there are some 20-minute episodes and two-parters, and Paige and I watched them all over the course of a couple of days.
Good on you, Steven Universe is a good rabbit hole to fall down!
Welcome to Tumblr, it can be pretty damn entertaining.