Shellac or traditional varnish are probably the only things you could put on your floor that aren't produced with an industrial process. Shellac in particular is the harvested secretions of a beetle that have been cleaned and dissolved in alcohol. But it's water-soluble and so probably not appropriate for use on a wood floor. You could also use tung oil or boiled linseed oil but you'd have to sand down to #0000 steel wool to get it to shine like urethane. Tung oil is a nice coating because it doesn't turn orange like BLO, but either one you will have to keep applying every few years or the floor will stop repelling water.

Obviously we'd end up with huge Tung plantations or Shellac plantations if we tried to replace all of our floor coverings with this stuff.