I have a faint memory that manussa comes from “mano + “ussa” and that would mean that we, humans, have the ability to change gati through mano, but is that right? Also what does ussa mean exactly (if it actually comes from mano + ussa)?
I don’t think it comes from Pali. However, in Sinhala, manussa (“mana” + “ussa“) means “higher mind.” Of course, maunssa is a word common to Pali and Sinhala.
However, it makes sense. Even though Devas and Brahmas can attain Nibbana, only a human (maunssa) can attain Buddhahood.