As I discuss in the this question, by far the most popular school of Hindu philosophy is the Vedanta school, which bases its tenets on the doctrines laid out in the Brahma Sutras, a work by the sage Vyasa which summarizes and systematizes the philosophical teachings of the Upanishads. You can read the Brahma Sutras here. In any case, Adhyaya 3 Pada 3 of the Brahma Sutras describes the Brahma Vidyas, 32 lessons found in various Upanishads which can each lead you to Brahman if you meditate on it. You can see the full list of 32 Vidyas here.
Now as I discuss in this question, one of the 32 Brahma Vidyas is known as the Panchagni Vidya, and it's found in the Brihadaranyaka and Chandogya Upanishads. Among other things, it describes the path of souls going to Brahmaloka. Here is how the Brihadaranyaka Upanishads describes this journey:
Those who thus know this, and those who in the forest worship faith and the True, go to light (arkis), from light to day, from day to the increasing half, from the increasing half to the six months when the sun goes to the north, from those six months to the world of the Devas (Devaloka), from the world of the Devas to the sun, from the sun to the place of lightning. When they have thus reached the place of lightning a spirit comes near them, and leads them to the worlds of the (conditioned) Brahman. In these worlds of Brahman they dwell exalted for ages. There is no returning for them.
Now the Sanskrit used to describe this spirit is Manasa, meaning created by the mind. Now the description in the Chandogya Upanishad is virtually identical, except for one significant change:
Those who know this and those who in the forest follow faith and austerities go to light (arkis), from light to day, from day to the light half of the moon, from the light half of the moon to the six months when the sun goes to the north, from the six months when the sun goes to the north to the year, from the year to the sun, from the sun to the moon, from the moon to the lightning. There is a person not human, He leads them to Brahman (the conditioned Brahman).
Here the Sanskrit word used is "Amanava" or not human, instead of "Manasa". So my question is, who is this being that escorts you to Brahmaloka? And is he Amanava or Manasa or both? Is it possible that the manuscripts of one of these Upanishads have an error, where the "va" was replaced by "sa" or vice versa?
The only information I have found on the identity of this being is this book, which describes him as an incarnation of Vishnu who leads souls to Vishnu's highest abode of Paramapadam:
From thence he proceeds to Paramapada through a dark spot in the sun. Supreme wisdom attained by Yoga directs him along the Path and the Ativahikas, bearers in transit, lead him on; they are certain holy souls named Archi, Ahas, Purvapaksha, Uttarayana, Samvatsara, Aditya, Chandra, Vaidyuta, Varuna, Indra, Prajapati, and lastly an incarnation of Vishnu, named Amanava.
But are there any scriptures that describe this being as an incarnation of Vishnu?