The usual leg wear at this time was a pair of breeches; the sort of loose, or open-legged items we would call "trousers" (or "pants" if you are American) were known back then as "overalls" and they were generally worn over the top of breeches in order to protect them from damage or staining. All legwear was much looser than is generally depicted by modern artists (and figure sculptors!) as they would be made baggy to facilitate movement. The narrow-legged trousers/pants worn by some of the figures look somewhat unlikely, but are not necessarily anachronistic as people on the fringes of society (geographically, as well as financially) might not have the material, or sewing skill to create anything better - at least not for work.
As you rightly say, sailors' "slop clothing" would include what would today be regarded as "long shorts" with wide-ended legs, designed for ease of movement. It's unlikely that civilians would have worn the one-piece gaitered overalls of the AWI-era soldier, as these were to prevent stones getting into the shoes on the march, when a man could not fall out of the ranks easily to remove them and had to maintain a certain speed.
Underwear (for either sex) was largely only for the rich and men generally tucked their shirts under their crotch for warmth etc; apart from a few wealthy Italian types, women seem to have coped pretty well without drawers until the mid-1800s (until a 2012 discovery of four mediaeval versions in an Austrian castle, the bra was thought to be a 20th Century invention).