I love the idea, the simplistic look and feel. Please continue this one!
I am however ULTRA low skill at jump'n'run .. I couldn't find a dedicated jump button, only the up arrow and was unable to figure out how to perform even the first jump .. somehow I mashed so hard I double or triplejumped but ended up dying to something.. and I wasn't quite sure what.. for every game that includes jumping, please have the jump button not as "up", that's impossible to access on a keyboard xD
From what you wrote, this was a learning experience and to kind of test and idea out, exactly what jams are for.
Platform controls were very smooth, I liked that :D