The very first art program i used was actually more of an in-app social media - Drawquest. Created by Chris Pool, the whole idea was that, every day, a new drawing prompt (usually a pre-drawn template) would be posted for you to do. This obviously incentivized people to keep coming back but it also was a great exercise in creativity. It was also the first time I had ever found an online community to join.
I remember it being one of the more popular art apps at the time, so the servers going down in 2014 was a shock to a lot of people... while reading up on this app again though i found out it became open source back in 2015. I don't have any of my own drawings from there anymore. Which is probably good cause they were toddler drawings LOL. But I do have a single item saved, and it's this:
My MLP oc, drawn by a very sweet person lost to time. ^^
P.S. That KidPix zine @TheFrugalGamer linked is crazy cool!!!