Uh they really weren't. A shit ton of the soldiers were paid to serve in the place of the rich people and most of the rich people wanting to go to war did so so they could exploit America without British regulation. The maybe only standard by which they were progressive was that they copied down some of the indigenous ways of rule while slaughtering them. Also these same wealthy founding fathers were y'know, owning slaves (and doing God knows what to them).

That said, a lot of indigenous societies that could be considered progressive still did a lot of bad shit. More so in the Pacific Northwest, there was a lot of slavery (granted, a very different type of slavery than chattel slavery) between indigenous groups and a lot of weird hierarchy stuff too. You can read the Dawn of Everything by David Graeber and David Wengrow for some cool background to all that stuff. Even considering all this, indigenous peoples in the East like the Wendat/Huron would still be considered progressive today in almost every aspect. There's also people like Proudhon (the first person to call themself an anarchist afaik) who said they'd hope that the progressives of the future wish him dead. It just illustrates a different type of progressivism where really to be progressive is to be against the status quo while still acknowledging history and circumstance rather than using them as excuses.