Buddha said " Satta "..in many Suttas. the meaning is " clinker person(person) " who clinging in 5 aggregates.
This " Satta "..is developing the 8 noble paths and ending suffer. And call person who " Nibbana of suffer ".. as.. Arahunt or Deathless-element or Unconditioned-element.
This is not " Permanent Ataman in Upanishad view "... I don't know why Buddhist seems to avoiding " Satta(clinker) - Puggalo(person) "...