This just gets worse and worse. I just discovered that all of the "starter avatars" that are in the inventory folder Library/Clothing/Initial Outfits are No Modify. If you go into Appearance mode, you can't save the results as an Outfit, or save the shape, or use it as a starting point for creating your own shape. The "Save" option is grayed out. This is true not only of the new Mesh avatars, but ALL the starter avatars.
In their attempt to insulate newcomers from all possibility of making mistakes, Linden Lab is making it very difficult to enjoy the wonders of Second Life these days.
My advice is to find some freebie stores and stock up. Then ditch the starter avatar as soon as you can and have fun learning how to play dress-up, SL style (and get frustrated, if that's what it takes.)