Sorry, I started with the very begining of the original dragonball run... So my proxy remains Goku as I'm in the same age group as he is...
Regarding Gohan, he's half sayan. So although he has an incredible potential, he probably lacks some of the pride and alpha hormones.
Future Trunks this ep was somehow following that same path. But chibi Trunks, well pushed by his over the top father, did put him back on tracks.

Regarding Zamasu, he saw that coming and used the time rings, or he was already immortal, or his wish in the future can create a time paradox ie: I'm immortal now, so even if someone kills pe in the past, when we get back to now I'm alive again.