As President Trump is not an MD and most especially not a Virologist he was following the advice of the government and other "experts", like Fauci and the CDC among others.
They were the ones who didn't quite figure out what to do.

Then there is the nature of the American People. We don't like being told what to do by"experts" or politicians. We don't like to be restricted in our movements and we are probably the most mobile nation on Earth. We are constantly on the move for work, shopping, just for fun and more Americans both numerically and % wise move addresses per year than anyone else. Not only that, but we also like to congregate for meeting, movies, sports etc. etc.
All of which tends to negate the anti-COVID measures if people were following them in the first place. Hell we even had door to door sales people coming around during COVID - we put a sign on our front door stating we would not be answering the door.

As to our large numbers of deaths during COVID, well take all the above and combine it with our nearly 340million (#3 behind China and India) population and our nearly 100% coverage of statistics and it is no wonder our reported deaths were so high.* China I am at least 99% certain did not give accurate numbers just for politics sake and India has many millions of people living in small villages and city slums who seldom interact with the government or report deaths, they just have a family service and bury them. Many people still believe that the dead should just be dropped in one of the sacred rivers so even if the government came by to check on the deaths from COVID there are no graves, just a body that drifted away on the river and was eaten by water life. So their numbers were probably even less accurate than China.

And then there are parts of Africa, parts of Asia & remote areas of So America etc. etc. etc. I saw articles of entire villages in Africa being a ghost town, no one to count the dead and when the government checked they just dug trenches with a bulldozer, dropped all the bodies in, burned the buildings to hopefully kill the virus and moved on down the road to check the next village. I saw similar things in Vietnam during the Tet Offensive, bulldozers and back hoes digging large holes in the cemetery next to our base and then trucks of bodies in piles pulling in and soldiers tossing them in until the hole was full, and a dozer pushed dirt over them then dug the next hole. That happened several times a day for a couple of weeks. So if you tell me it didn't happen in many places during COVID I will call you ignorant if I am in a nice mood and a liar if I am in a bad mood.

*Remember all the reports that many places deliberately over counted COVID deaths for benefits and aid? Someone comes into the ER/Trauma Center/Morgue dead from a traffic accident, heart attack etc. etc. and they also had COVID = just put them on the Covid death list. It was a lot less work for the severely over worked medical staffs. Who were already running to another in the endless line of patients or bodies coming in. No string of lab tests to determine the cause of death, no need for an autopsy etc. etc. just put another name on the COVID list. Reportedly that happened in a lot of places around the world. Too over worked to test and make accurate records.

No, trump absolutely ignored the early warnings he got as early as December of 2019.

By the time trump finally assembled his Covid response team, the "horse had already bolted out of the barn" so to say.

The mistakes trump made in not taking corrective measures after FAILING a disaster recovery exercise in 2018 and dissolving the pandemic response team contributed hugely to trump's disastrous Covid-19 Pandemic failure.

It's coming out that trump's Covid-19 response team had their hands tied in what they were able to say publicly, or risk being let go by trump.

Remember that trump didn't want testing done, just to keep the number of confirmed cases low!