No one in the past took the extraordinary measures we have or had anything approaching our level of medical technology. It would have been a LOT worse if it had happened in the past. Plus, China’s numbers and other countries’ numbers have been significantly undercounted.
Those are good points to keep in mind.
Absolutely.
The discovery of bacteria by van Leeuwenhoek wasn't until 1676 - and the significance of them was not known until the establishment of ‘germ theory’ in the mid to late 19th century. Viruses weren't discovered until the 1890s, ~20 years before the Spanish Flu pandemic. Penicillin wasn't discovered until 1928 (Fleming).
Influenza was first isolated in 1933, and widespread vaccination didn't begin until ~1945. The structure of DNA wasn't discovered until 1953. The first antivirals were proposed in the 1960’s.
The bottom line is that it's very hard to compare the virulence/lethality of all these different infectious diseases, as they occurred at different times in history.
It is becoming more and more obvious that this one wouldn't have even been noticed in the past. It would have been lost in the noise of the seasonal flu numbers. Nothing that governments around the world have done have been effective, largely because their reactions have been based on models using false assumptions.
The R0 of smallpox is much higher than for the Wuhan Flu. We did not shut down the country. We quarantined the sick