"The Origin of the Family, Private Property and the State" by Friedrich Engels

Apparently, most of Marx's work is not exactly based on historical data. Though the materialist approach Marx and Engels take is based on the observation of history from a materialist perspective. They believe that material conditions drive history rather than ideas. (One could also argue that it is part of historic determinism) This is certainly interesting but it opens the room for a lot of speculation.

Engels claims that primitive tribes were communist and egalitarian, though there are other contemporary claims that marxism is not based on egalitarianism (confusing). Since history is driven by material conditions wouldn't going back to this model make us more regressive than progressive? (as I understand it is a specific set of material conditions that forced our species to shift on how we organize society - some good, some not so good)

So what meaning is there is to "forcefully" change the material conditions if the time for it has not come and also on what non abstract basis?

I am very sorry if this seems like a loaded post with a lot of questions. Mostly looking for answers to the question in the title of the post. Thank you very much.