The problem(s) in America was that there was a long delay and period of downplaying the virus before any lockdowns occurred. In other words, it was already late and spreading when the belated lockdowns occurred.
Secondly it was rather patchwork. State by state. And in some states, county by county. if one county in FLA or CA closes their beaches, but the next county has them open, the lockdown in one area is largely undermined.
Biden should hammer home No Coordinated National Response.
Say that every time a human is within earshot.
I think that's pretty easy to understand and a succinct indictment of Trump's handling. Can add specifics and details and how Biden/Obama would have handled things. But get that core message across.
Have to say Hillary's competence and mastery of gov't and details would be perfect about now. I think she could chew up and spit out this failed version of Trump. Hopefully the Biden folks will get her out on to some news shows. Or at least get some advice and approach from her. Pull out all the stops and have Obama involved as well. If big rallies occur, Biden should have Obama at his first one. Dems past and present should present a united front in support of Biden. Obama, Hillary, Michelle O, Sanders, AOC, Warren, Kamala. Make it clear this is too important an election to lose. Drive turnout. What will the GOP do, counter with W Bush .... ?
Also, correct a mistake Hillary made last time. Start early pushing for a DEM Senate. Make the case that we need a Dem president and Senate to get things done. And list what those are. A return to competency, normalcy, removing corruption. Health case access for all. Solar and wind over fossil fuels, especially phasing out coal. Climate change action. Wealth tax and especially taxing corporations. Big infrastructure projects to rebuild the country. Etc.