The travel ban didn’t help much. There were thousands of US citizens flying back and probably hundreds of them already carrying the virus. The travel ban most likely slowed the spread down but looking at the situation today, it was insignificant.
But you had to go into lockdown, and shut down the borders everywhere. This is what Trump failed to do.
The virus actually came in from Europe. And when they finally shut down travel from Europe, and everyone immediately flocked home, then this caused the east coast to explode in infected cases.
And New York was just a Petri dish, that the virus was incubating there for weeks.
The problem is the impossible standard. Every government was caught off-guard. South Korea handled it the best, but they have the preparation from the worry about chemical warfare from the North.
There is no precedent for stopping the economy for a virus, we didn't do that for Swine Flu or any other pandemic.
I'm glad this is the new standard, but lets not pretend it's always been.