Cephalization is where sensory organs and nerve tissues concentrate at one end of an organism, forming a "head" area. Just because it is so common for life on earth to exhibit this tendency doesn't necessarily mean it occurs everywhere. It could simply be the evolutionary effect of a common ancestor to all animal life on our planet. Then again, given the vastness of the universe, I'm reasonably certain there are many earthlike creatures out there somewhere.

Certain characteristics, as you mentioned, make evolutionary sense. Fins for water creatures. Legs for land creatures. Areodynamic wings for flying creatures. The article mentioned the very large eyes on the froglike alien resulting from the dark environment produced by K2-18b's Red Dwarf sun.

K2-18b will certainly get much greater attention in the coming years. It is the JWST's most significant discovery to date without a doubt. The planet deserves a better name at this point. What about Proteus, a sea god from greek mythology?