This is great for a first game! I really like the parallax effect you have going on.
A few tips for you:
the platformer jump should be going up slower but coming down faster, so it's useful to have two types of gravity.
add a foreground layer to games, I personally enjoy it when there is something like a world in front of the player too.
Other than that, the game looks great! I would have loved to see some more gameplay though please expand on this! I would love to play it!