You do not seem to understand what the actual purpose of the vertical trim system is. It is roughly equivalent to cruise control on a car. It greatly reduces the work load on the pilots but is not essential for flight safety and can be turned off.
And you don’t seem to understand that the MCAS system is a system that over rides pilot controls... in the model of the plane that crashed in these cases is a model of the plane that allowed the MCAS system to override the pilot based on a single sensor input, That is a single point of failure and there is no way the FAA would certify air worthiness for this model had they known this. someone(s) lied, they either lied about it kicking in with only one senors input, or they lied about only having one sensor as input in that model.
I’ve done government hardwares and software certifications, there is no way this model got airworthiness certification without fraud. None.