Trumps campaign was a stupidly run disaster that forgot most of what got him elected in 2020.
Yes, he should have hammered Biden on NAFTA/WTO.
It was painfully obvious that the Trump team expected Bernie to be the nominee, and they never really pivoted away from cringey canned lines about SOCIALISM. Outside of South Florida it didn't really win him any more votes, and as you said there were far better things to hit Biden on.
They would've thrown this line out if Bloomberg won. SOCIALISM is just the default against any Democrat.
But really, COVID was the main issue at play and Trump botched it! Those other things just didn't really matter much.