All are good except i dont quite like the last one. The man seems to holding a plastic bag.
I think all are fine except the one with the man's butt facing the photographer.
RICOH GRD I / II / III / IV / GR / GXR
I think its all to do with the portrayal of scale... and in the last shot, how a "beautiful" shot in the eyes of one, may be nothing more than "same-ol' same-ol'" in the eyes of others (ie, those walking along the path)
I think they are all fine, especially the first 2. The 3rd one isn't particularly flattering, but it is perhaps interesting.
As catchlights said, it adds interest into the photo. It's really about what the photographer wishes to present.
can add sense of scale,
for example, a small man, amidst a sand dune, that will tell you just how large it is?
it is down to personal preference,
personally, i think no landscapes should have humans other than that sense of scale purpose.
With digital nowadays... there is always the "median" function to make them all go away... Shoo! Humans begone!