I actually think the flush toilet should be number one on the list.
The modern flush toilet by itself is no big deal, they used to use a constantly running open trough to get rid of sewage.
Those running troughs dumped the sewage directly into the closest stream, river, lake, or the street gutter outside your home.
Read about JOHN SNOW’S investigation into the CHOLERA outbreak in London in 1854.
What is a big deal from a health and sanitary standpoint is MODERN SEWAGE TREATMENT methods.
Closed systems that don’t allow polluted water to enter your drinking water system.
Most folks have never seen a surface cesspond, I have, very disgusting and smells just like you think.