Oh yes, once upon a time Hitler and Mussolini were two of the most popular politicians in the Western World.
Media darlings in fact!
They were imaginative socialists at a time when socialism was very much in vogue.
Twas their leftist minds that dreamt up fascism.
Somewhat ironic that fascism is largely branded a right-wing thing today.
Well, you're not completely out to lunch... but you're not right either.
Mussolini was a communist before he became a fascist, and he borrowed a lot from communism when creating fascism. This much is true. He himself also suggested that fascism had a lot in common with social democracy, which is the mellowest form of socialism, but all social democrats vehemently protested against this statement.
Mussolini in turn inspired both Peron in Argentina and Castro on Cuba when they tried to build in corporativism in their societies. Thus these Spanish speaking socialists borrowed ideas from fascism.
But there was never any question about on which side of the political spectrum the fascists and/or nazis belonged. At the core of their ideology lies traditional values regarding family, church and nation. In sharp contrast to the communist tenets of breaking up families, of atheism and globalism.
The genius of fascism was to incorporate populism into a right wing agenda, which allowed them to woo the working class and made them very different from conservatives, but still firmly planted on the right wing of politics. It's kind of like the difference between Steve Bannon and traditional Republicans. A lot of blue collar Americans feel that Steve Bannon and his alt right movement is about their rights, but in truth it's all still just about making the rich richer. They're just saying it in a way that makes white trash believe they and the one percent have a common agenda.
How did Hitler get to power? Well his NSDAP got just over 30% of the vote, but thanks to forming a coalition with the Conservatives, he was able to become chancellor and assume power. Just like the Conservatives in Sweden are the only party to have ever considered cooperating with the Sweden Democrats, a party with neonazi roots.
What was the first thing he did? He banned the communist party and had many of the prominent communists arrested and sent to concentration camps. He later did the same with the social democrats.
The first people who were rounded up and sent to concentration camps were those on the left wing. Communists, socialists, union organizers. Then he added homosexuals, and eventually Jews, Gypsies (or Romani, as they prefer to be called these days) and other ethnic, sexual and religious minorities.
If Hitler, as you claim, was left wing, shouldn't he have rounded up conservatives and priests instead of his fellow left wingers?
Furthermore, look at the fascist regime that survived WWII; Franco's falangists in Spain, that ruled that country till 1975. Look at their policies, priorities, their allies and their enemies. They were right wing. No question about it. Women did not belong in the workplace, they should stay at home and take care of the family, while having as many children as possible. Companies in theory had to pay taxes, but they did not need to present any book keeping, so they were only taxed on any profits they decided to reveal. Most companies claimed to not make any profits. Sort of like Donald Trump's businesses. The church was extremely powerful. The poor extremely poor.
Communism and fascism in many ways resemble one another; they are both authoritarian, they both scoff at human rights and minority rights, they both hate homosexuals, neither ideology understands the benefits of free trade, they thinkdemocracy is a sham, etc. But in a communist country private companies will be confiscated and turned over to the government and the government will provide healthcare and education for all.And in most communist countries religious people will be persecuted. In a fascist country the upper class will retain its privileges and possessions. Worker's rights are on the other hand extremely limited and trade unions are illegal. The church and traditional family values are at the core of society.
Another huge difference is the matter of class. In communism and socialism the concept of class is fundamental. They see society as permeated by class struggle, and they are firmly on the side of the working class (at least in theory, in practice -not so much...). In fascism the concept of classes is frowned upon. The idea is that the Nation is sacred and that people from all walks of life have their place in the structure and should all be pulling together. Hence the corporativistic ideas, where different groups all should be represented in local councils etc.
According to communism, the working class around the world should rise and overthrow their rulers and form one great alliance with the proletariat calling the shots.
According to fascism the different classes should cooperate in building a stronger nation. Well, in theory. In practice the poor get royally screwed. And when they complain they get punished for questioning their god given position in the social order.
Suffice it to say that communism and fascism are equally bad, and far inferior to the concept of liberal democracy that has become the norm in Western civilisation.
But it is quite easy to differentiate between them on the left-right scale.
No matter how loudly you insist otherwise.