Uller
Adventurer
You could say that but I wouldn't rule it that way.
Okay but I've found that if you nerf a PC ability away from RAW you either need player buy-in in advance or you better have a really good criteria for when and how they can use the ability so they don't feel like they are playing "DM may I". You seem to be keying off of flavor text ("...step from one shadow to another.") and ignoring crunch (When you are in dim-light or darkness..."). That's fine....sometimes RAI and balance can be found in flavor text. So you just need to be very clear what constitutes a shadow. Generally any area of dim-light or darkness is a shadow of some sort.
I stick to the "dim-light or darkness" rule because it makes the ability generally useless in a lot of situations. If there is not a specific area of dim-light the monk can't use it. The monk in my party is a wood-elf so she has dark vision to 60' but a human shadow monk would not be able to shadow step to an area of complete darkness because of that pesky "that you can see" clause.