This might had been the case in only low density areas (same as in all other continents), the majority of indigenous Americans did not live in classless societies.
Nobody said no classes. There wasn’t money like there was in Europe. There were by some intellectually honest estimates 50m people living in N and S America at the time of arrival, a huge number of people were living day to day without money.
Indigenous Americans practiced warfare, rape, slavery, and cannibalism no different than other peoples around the world.