The biggest thing I noticed was that the collision shapes are too large for the images, especially the spikes. I tested on the first spikes on the starting level, and had a very clear several pixel gap between the player sprite and the spikes when it collided and I took damage. This was most noticeable when jumping over them only to find the triangle spikes seemed to have a square collision shape. It also feels like the collision shape does not change when the animation shows them as being low. I again used those first spikes, and timed a jump to land when they were down, but it showed the collision with a large gap between the player sprite and the spike sprite.
Through testing I figured out that there is wall jump, wall slide, and double jump, but it would be nice if it was noted somewhere what the abilities are. Platformers can have so many different abilities, letting players know which you've included helps.
The controls are decent. Platformers aren't my usual style of game, so I can't compare to many, but they worked well enough for me once I played around a bit.
When you lose the game over screen includes some stats, but getting to the end does not. It would be nice if the final room also included the stats.