That entry door seems level, or even slightly above, the adjacent sidewalk. Was it built that way, or was the door raised and that little bridge added later? In which case you’d need steps inside the doorway in order to be standing on the first floor.
They raised the streets to get them out the swamp that Chicago was built on. If you go to downtown Chicago the city is built up about 20 ft. It’s really visible at the river bridges, or union station, the bridges over the river are flat, and the trains go flat into a basement. Prop who live in those houses can have storage under the sidewalk, and they were often the site of the outhouse in the late 1800s. It’s a fascinating read the raising of chicago
I have never been inside one, but have read that all possible variations to accommodate the adjusted elevation can be found.