#15 - Very nice. The waves come off looking a bit like an ear. If there could be another element of the dark one coming up form the bottom left, I think that could help. What you have there does have the wave cradling the "infant", which is nice. Basically help the dark one look more like a wave & less like an ear.
#16 - Again - very nice. I'd lose the image of the "Darker" person (if that's what it is - it took us a little effort to make out there might be 2 people in there, one a reverse image and the other not), and make the wave less of a "drippy" curl. I love the bottom person sleeping, but as you lose the 2nd "darker, higher" person, maybe slide the bottom person up & into the wave a bit of you can make that work. I'd start the background on the left lower, so it's more balanced, but make this a lower priority. If you make the other changes & you like where the background starts, lets take a look. I'm leaning away from aqua's, so you might try a baby blue or darker blue for the wave background.
#16 - Now that I read your comments, I cna see that this is a mother cradling her baby. I didn't get that though until I read your comments. If you want to pursue that concept, maybe there's some way of making that clearer at a glance.
I still wouldn't mind seeing a single person in the wave, especially if seeing the 2 people isn't clear at a glance.
#15 - If you get the chance to add something to make the left, darker part of the wave/mother, to look more like a wave & less like an ear - I'd still like to see it. It would be a real contender with that, but I can't rank it higher when it still resembles an ear.