In many ways, it really is - I’ve not actually got textual sources to hand, because I learned the concept experientially, via core shamanism where it’s a key concept.
it has aspects of the Greek daimon (as I understand it from lightweight study), aspects of the HGA, and contains a hefty dollop of the “Earth school” theory very popular amongst the new age love and light set, that we incarnate to “learn lessons” and shed attachments.
This has the eastern-derived goal of eventually realising we are One with both all things and the All, with which we then merge forever, thus fixing the inexplicable error that is life - I prefer the concept of life as a game, life-as-a-mistake actually fucked me up pretty badly, but that’s getting near to off-topic. 
I outlined something I did to break free from that simplistic paradigm in which the HS takes a kind of parental role, whilst retaining its power, here: Evocation Of My Personal Daemon
That was in late 2013 - I’ve been very happy with that bit of work, and more conventionally, I’ve successfully healed humans and animals using their own HS as given in core shamanism as well, so I find that while having a concept that there’s a Higher Self, an embodied self, past lives, dead people you can still talk to, and reincarnation, is all a bit of a jumble, it yeilds results, reliably, and I continue to use it and recommend it for that reason.