Shemlen really just means "quick ones or quick children" The humans were called that because of their short lives by the immortal elves so, to them, yes a modern Dalish IS a shemlen as much as a human is..
All we really know is that shemlen means human, aside from its literal translation that is. It is derived from the words for quick and children in reference to their mortality, yes, but there's nothing to suggest that calling a Dalish elf a shemlen actually makes sense. I mean, why would it? Because both are mortal? That'd be like calling an apple an orange because both are fruits. And both are mortal, I guess.
But hey, words can have multiple definitions, I guess. Or Abelas literally called the inquisitor a human, but that's just silly. And rude. Which might have been the point, I suppose.
I'm too tired to think about this anymore.