I'm not sure a travel ban would ever have been effective. The disease had probably moved out of Wuhan before anyone there had got sick, or, certainly, before anyone had a chance to recognise this for what it was.
Maybe bringing it in sooner would have reduced the risk of spread in the US, but the problem is that even then a travel "ban" still means that your own citizens have to return home, and you still have to be able to detect the disease in order to screen it.
None of this means that I disagree with Trump's decision to have imposed the ban, from either China or Europe. It may not have been effective, but it made sense to try.