I think there's many conflicting views as to what indigos are. The same with wanderers ( starseeds ). What's the consensus?
Bc to my knowledge, indigo only started incarnating around the turn of the millennium, circa 1996 and on. Their arrival completely coincided with the rise of "clinical autism."
The older generations that have some similar abilities and design as indigo children are considered "wanderers" by The Law of One. ( If you've never looked into the Law of One, I highly recommend it. You may not agree with every single thing in it, but you certainly won't regret reading it.) So wanderers aka starseeds are those who's soul's are from elsewhere that incarnate into human bodies in order to aid humanity in a myriad of ways. The Pleiades are a major home star system for many wanderers, though not exclusively. Their origins are widespread. Orion, Sirius, Vega, Arcturus, etc.
Generally their souls descend ( temporarily )from either 4th, 5th, or 6th density to serve a multitude of purposes. All of which are in aid to humanity.