I've always taken the entire "America will win again" and "Make America Great again" as an economic argument - that your lives have gotten worse due to globalization and trade and etc etc, and that we're gonna take that all back.
I think there are a lot of liberal leaning folks who desperately want to believe that it's just about social interests and racism and sexism because it makes it easy to just paint him a straight up mustache twirling 100% bad guy, but I just watched him defend PP on a GOP debate stage, and he hasn't touched gay marriage or bringing back the ten commandments in a courthouse.
His primary arguments are motivated by economics - even his immigration argument. There are enough dog-whistles to grab the racists onto his side - but I think his primary argument that resonates with people (and is what the GOP establishment is getting side-swiped on) is the economic one. It also explains the weird Bernie / Trump overlap on voters (and why Bernie would trounce Trump specifically while not doing as well against the other GOP candidates).