Wow, that surely is convincing...
Genetics, just like the other sciences, even when simplified, is a broad and specialized topic that most have had near zero formal education in; very basic if any. Book smarts ain't always dumb... The basis for the phylogenetic tree depicted is exactly the connection you sought. I personally think life came to Earth from elsewhere, possibly more than one type and one time, and by an unknown mechanism. So- there's lot's of unknowns, but there's for certain shared genetics among the lifeforms on this planet.
