Interesting approach on the theme. I think the idea that you have to protect the wagons at the end, but make the train faster at the front (also heal yourself), very creative. It creates a feeling of chaos in me, because sometimes i don't know exactly which one has more priority. So basically, you have to strategically consider which of the two mechanics seems more important to you. Very nice!
I would have liked that you implemented more mechanics around these two core mechanics. But we're here in a 48h jam, so i can unterstand that you didn't do it.
All in all, i really liked your game. Great work!