Hey! Thanks for playing! The jumping is a bit sticky, yeah. You needed to let go of the arrow keys when jumping to make it work, else the movement velocity holds you against the wall. I didn't have time to fix that bug... 12 hours is pretty tight.
As for coins being where you couldn't get to, some of them were randomly spawned by one of the other devs.
At the end, if you jump on the platform above you can get a better view of the Sirenheadosaurus!
And you're right, we should have had a "Start" button at the title screen so you could read the full beginning of the madlibs.