First, excuse my English. I'm using a translator, to be faster. I think you will understand me.
I have been playing for about 26 hours and, from my experience, I propose to improve the crafting system. Mainly I think that it is necessary to improve the probability system with which we manufacture tools and build buildings.
For this, I can think of two ideas:
The probability of building or manufacturing is somewhat higher as you approach the level that allows you 100%. It is not very normal that with one level less the probilidad is reduced, in the majority of the cases, to 50%.
That the top-level building tools offer better odds. For example, if I built a palisade with a copper ax, I would be more likely to build it than with a stone ax. I think a speed improvement is not enough.