... I just find it highly implausible that if this is the truth that random mutations is the mechanism that led to all the complex coordinated life systems that exist.
It's not "the" mechanism, it's one of a couple dozen mechanisms.
The jumps from non vertebrae to vertebrae and asexual to sexual reproduction are the most problematic for a Darwinist to explain without sounding completely ridiculous to me.
Which part of the vertebra development is difficult? Centralizing neurons into a single cord? The gradual formation of a bony shell around the cord?
Why is it difficult to believe that the two processes of replication and syzygy merged into one process?