Tumblrina here.
Tumblr is pretty active even to this day, most of people there tho belong to fandoms so most of the content there thrives if it's targeted to either a very invested franchise (Superwholock aka Supernatural, Doctor Who, Sherlock or anything similar to that) or a currently airing series and whose fandom will die once it finishes.
Original art doesn't do very well if you're not constantly pumping artwork, making memes, having the pages accessible within the site or a very organized blog where you can get the lore quickly, many people that thrive with their original content usually used the strategy or making fancharacters and eventually separating them from the original franchise it was inspired on.
I personally like it quite a lot, I feel is a bit more organized and easy to customize, most of the art stuff and resources that I drop in the Tapas Art Master Library is found from there