Answer 1

For a first map it wasn't bad at all. I talked at length about it on my stream, but a few summarizing suggestions:

Why does the ground just end right below the player? You do a great job adding background, even some parallax in certain spots, but its very jarring to have a huge empty space, above and below, this rectangular dirt box you've created.

Not sure why there is one random pillar of grass rather than dirt.

The middle section is a bite stale. A bit more variety would make it more interesting to play, instead of having the same turkey three times in a row followed by a tiny hallway with enemies. Also in that section, I would do what you did up top and make it so you can't just walk into the spikes. Instead make them 1 tile below the player so there is a little ledge.