Thank you for your honest feedback :)
I totally agree with the points you mentioned. Hopefully, if we decide to keep working on this, we can improve the gameplay to make it more fun and give clear instructions on how the game functions.
Thank you so much for pointing out the 3D character and cutscenes. Really glad you liked it.
Did you try pressing "Q" for quick spawning more plants? I don't know if this would have worked for sure, but I encountered the issue once myself and "Q" helped fixing it. Maybe, if you are interested in giving it another try, this would work as a solution.