a log house with a low crawl under space. How to insulate the floor?

Hi,
I am new here and if such a topic is somewhere, I would appreciate being lead there.
We bought a house from 1909 in Sweden. When reconstructing, we needed to take the mixture of soil and sawdust out from under the floor because the house was inhabited by mice and it was all stinky. Under the original floorboards, there was about a 15cm thick layer of this mixture that laid on thick wooden boards. What shall we replace it with? We were recommended by the locals not to go for new materials of the 21st century. We were advised to keep this mixture but no matter how much we were trying to air the room, this unpleasant odour was still there, so we took it out. There we found bones of dead animals, as big as a cat. I am glad we did it. Any suggestion? Thanks a lot

Here is the short video

Can you replace like with like?  Sawmills can provide huge quantities of fine sawdust for you.

I suspect that the locals know what they are taking about. Traditional structures need to breathe, and a thick layer of dry sawdust/soil will both insulate and regulate humidity.

I had a similar situation when I rebuilt my old log cabin. I took all the old drbris out. Then I put a vapor barrier on the ground, 3/4 plywood on top of the floor joist then 1" of insulation board and then 1/2 plywood underlayment on top.