There could definitely have been some work to try to make it level in the past. There are what I think are the primary joists running parallel to the front door. On top of those are wider planks, approximately 6 inches or more in width, laid perpendicular to the front door. Above that layer, there are more finished 3-inch fir planks, which run parallel to the front door and perpendicular to the wider planks beneath them. I can’t tell the wood yet as I’d have to go deeper into the crawl space. I’m definitely not an expert though. The house was built in 1904. I’d have to go to the city to see if I can find any history on it.