How is it possible that Bitcoin is a stepping stone, when the code is open source and can change? It's not stuck and frozen in time, it can evolve, right?
wrong... the bitcoin core devs have stated many times they wont change anything unless 100% necessary! so yes bitcoin will stay the way it is unless something comes along and threatens the protocol and demands a change to the protocol!
Not true. Was P2SH 100% necessary? It is unlikely Bitcoin will be changed for slight or trivial reasons but the idea it won't evolve is simply not based on history.