We have 560,000 cases in this country. Travel bans are helpful, but when the virus was already out of China, a travel ban without testing is useless. This is especially true when we already had cases in the U.S. in January. Every other country had to deal with a lack of transparency from China and some did it well and others did it poorly. The guy who compared Covid-19 to the flu in March did it poorly.
Countries that put into place social distancing restrictions as soon as they had community spread have fewer deaths per capita than we do. This includes Canada, Australia, and Norway. But there are many others if you'd like to take a look. https://www.worldometers.info/coronavirus/
Trump would not have needed the previous Supreme Court case to be able to shut down travel from a country during an epidemic. The previous case was only contested because Giuliani and others made it clear that the motive for their ban was based on the Muslim population of the selected countries. Additionally, you mentioned the first amendment in a previous post which you also don't understand. You don't have a first amendment right to post on a private forum because the entire bill of rights only proscribes government conduct.
I actually think you're a Trump supporter or you wouldn't possibly be able to think he did a competent job. In late January the characteristics of the virus were known, including how transmissible it is, the case fatality rate, and even the genome sequence. It was not only sequenced in China, but French scientists sequenced it before the month of January ended.
We also have reports of hospital workers who had to wear trash bags to work and re-sterilize masks for weeks on end. The President has a tool called the Defense Production Act which allows him to have any manufacturer make these things. He preferred to let front-line health care workers not have equipment than to invoke it. But yeah sure, being the leader of the richest country in the world and endangering health care workers by not providing them the right equipment is a sign of competence.