Thanks for playing and the detailed review! Here's my view on your feedback.
I purposefully made the game slow because I'm making unique art for each level. Its fine to race through repeated tile-sets but I'm trying to keep Seedlings grounded in reality. I will likely make the box and the wall climber creatures a bit faster though.
Having changeable seed colors to change the mechanics of current creatures is a cool idea but I'm trying to keep the tutorials to a minimum and that would get overly confusing fast. Also the art style is based around the current seed color. Most other colors wont look natural and will feel out of place.
With keeping with the grounded in reality theme, making more types of tree creatures, each with their own mechanics as the game progresses makes more sense. There's 5 more in the current build of the game.
There are more hazards later on in the game.
Thanks for taking the time to review and I'm glad you liked the photographic art style.