I can understand your arguments, but America had some currents similar to some Fascistic views, some made their way into the America First Committee, and sympathizers of Fascist leaders and ideas(Henry Ford): racism in the South against blacks, Isolationism as a way of mantaining American power on the Western Hemisphere, Antisemitism existed as a current and could have been exploited and the Keynesian solutions favored by the Democrats IOTL could be extended and redesigned towards several TVAs, an earlier Interstate Highway System and more welfare to support the population in a National-Socialistic fashion.
NOTE: I'm not saying the New Deal was Fascist, just that it could have been extended in a Fascist way.
None of that indicated fascism, as both a political or sociological phenomenon, was in any way likely. Most people recognize that right wing authoritarianism and fascism are not really comparable, and the same applies to vaguely social democratic or welfarist policy. Fascism entails a borderline revolutionary adjustment of the administrative structure of a country, with second order impacts within intermediating institutions through a turnover or reaccomodation of existing and new elites
I'm not really following how Isolationism follows to Fascism, which was an inherently revanchist doctrine in almost every country it existed in, perhaps with the exception of Brazil. I suppose if there was some territorial claim to areas of Latin America, maybe this could be a thing, but there was little to suggest that. The Isolationists for what its worth were never all that keen on Fascist countries. There was some admiration for Germany in the early-mid 1930s (not nailed down by ideology, it should be noted), but by the time of Kristallnacht and the march into Prague, that was gone. Their point was more an expression that America had no national interest in who won the European War (which was dumb but somewhat widely held) and that America had been duped into joining WW1 (also widely held, perhaps not as dumb, but not spot on either).
The most vigorously anti-Fascist members of the American government in terms of their foreign policy views, it should be noted, were the Dixiecrats, who consistently supported Roosevelt's opposition to Germany, Japan, and Italy, while also engaging in efforts to promote opposition movements even in Hungary and Romania at the time. The Republicans had a large isolationist wing, and the liberal wing of the Democratic Party joined it in the frenzy of the Nye Hearings. Anti-Semitism was real, but it was not a strong political force, and anti-anti-semitism tended to get far more results in terms of political organization. The Great Depression saw a much lower rise in anti-Semitism in the US than in most industrialized countries, and was a fringe force in the anti-Roosevelt opposition.
I think a case can be made that many New Deal programs had similarities to those enacted by Fascist countries. But I don't think you can divorce the era from that, as the 1930-1960 period saw immense mobilization and state power in the ascendancy in most countries in the world, and nationalizations of industry, public work programs to deal with unemployment, massive state owned enterprises engaging in infrastructure projects, capital controls, and just a general growth in the power of the state were things you saw in countries that were liberal democracies, fascist and communist dictatorships, monarchies, authoritarian juntas, social democracies, and all forms of government in existence. Put it this way: the construction of the Autobahn and the establishment of the German Labour Front did not make Germany unique, or Fascism unique, for that matter. Even the most fascistic act by Roosevelt in my view, the internment of German & Japanese nationals, was something that basically every combatant in WW2 to some extent or another engaged in.
