Conveyer belts should consume electricity.

There was something called Stone Age Mod that did pre robot industries but it seems to be gone. I could imagine a mine with sprites of little characters swinging pickaxes.

I don't have any problem with flying.

For the early game you could have workers/colonists that could perform the role of starter tier 1 buildings so you don't need magic buildings like automatic ore crushers made from only stone and steampunk gun turrets that don't need electricity.
Workers ...

Placed buildings have a timer countdown while they are "under construction".

Workers that are needed to make various buildings. Low tech buildings need more, automated buildings need less.

Workers are made in a house building and require food from Angel's bio mod. The lowest tier assembly building needs many workers. Higher tier assembly buildings have automation and ...