Well for a start it would take real talent to be worse.
I think Corbyn is as bad a ditherer as Johnson, but I think he would have -
Attended COBRA meetings and not gone on holiday for two weeks in Feb.
Had a four nation approach and got the other leaders more involved.
Been more worried about health than business and locked down sooner (which would have been cheaper anyway).
Postponed end of Brexit transition and put the 30,000 (or however many) civil servants on covid instead.
We wouldn't have had the corruption and billions flying out the door to ministers mates to (not) deliver contracts
He would have used existing council and health networks such as environmental health for track and trace.
Unfortunately I don't think he would have been able to set up as extensive a furlough system. Can you imagine the right wing press and public baying for his blood if a Labour government had put that in place? Likewise with lockdowns, the Mail would be comparing him to the Nazi's, I think he would have got away with lockdowns though and managed to do them. I don't think he could get away with such a generous furlough and grant scheme though.
On vaccines, I think this government have done well, I don't think he'd have done better.