For example, Oxford defines fascism as an extreme right-wing political system or attitude that is in favour of strong central government, aggressively promoting your own country or race above others, and that does not allow any opposition.

It's right-wing, ergo it is built on Capitalism and Corporatism. You've debunked yourself.

There is no specific economic system required for a government to be considered fascist. Historically, fascism has grown out of more socialist nations than capitalist. That doesn’t make fascism inherently socialist either.

That's a wild thing to say, and completely historically inaccurate, fascism has risen out of corporatism, ie later Capitalism. Nazi Germany, Mussolini's Italy, or even fascist movements like the British Union of Fascists have all been right-wing Capitalist ideologies.

Joseph Stalin stated in a speech in 1924: Fascism is not only a military-technical category. Fascism is the bourgeoisie's fighting organisation that relies on the active support of Social-Democracy. Social-Democracy is objectively the moderate wing of fascism.

Stalin is generally correct here, yes, which aligns with Umberto Eco's 14 points. Fascism arises during Capitalist crisis, and is a violent tool of the bourgeoisie to collaborate with the "middle class" against the lower classes. Social Democracy is Capitalist, with safety nets, not Socialist in any manner. You continue to prove yourself wrong.

The definition skews depending on the source. The qualities change depending on the government. The policies vary depending on the leader. The only consistent factors are the ones I stated earlier.

You're wrapping around to your vague initial point after debunking yourself this entire comment, for some reason.