I agree with Yaarel.
The role of the shaman was a healer, prophet, and keeper of history and tradition. Bards were healers, prophets, and keepers of history and tradition. The reason to go with bard is the very similar function because bards are similar in their roots. Bard's association with "echoes of these primordial Words of Creation" sounds pretty primal.
Any 3 musical instruments can also be thematic. Rattles, stretch drums, etc. If you read Singing to the Plants by Stephan V. Beyer as an example you'll find discussion on performance in shamanism as well as the icaros, which are the shaman's songs. These songs are given to the shaman (per that example) by the spirits of the plants and animals for things such as healing, protection, attacking, etc.
So for example using the game terms and mechanic I would take bard as the class and would likely use a custom background but acolyte works. At 1st level bard that would give applicable knowledge, religion, and insight. For bard skills I would probably add history (because it was a main part of the historical role) and that leaves two more skills that a player might think are thematic. I favor the knowledge / mystical aspect so arcana and nature.
Cantrips would be minor illusion and prestidigitation. Spells might be animal friendship, speak with animals, identify, and cure wounds depending on the theme. I'm keeping it mostly nature. Depending on the level of supernatural or curse feel Tasha's hideous laughter, sleep, bane, dissonant whispers, or command are suitable to use or add at 2nd level and maintain the theme. The important thing is the spells that the players take match the theme that player is looking for as the character levels and bards are good for that.
Lore bard is generally a good choice for most concepts but spirits bard already has a built in connection to the spirit world that fits better. My expertise would be in history, arcana, religion or nature, and insight.
Whether scholar, skald, or scoundrel, a bard weaves magic through words and music to inspire allies, demoralize foes, manipulate minds, create illusions, and even heal wounds. The bard is a master of song, speech, and the magic they contain.
Just... no. For one, I've already stated a preference for expanding broadly structured classes over refluffing less broad classes to fit an unconventional theme. The core concepts of the shaman are trances, fetishes, tribal community, vision questing, care for the sick/injured, and commuting with spirits. More important, they are primal, not a product of collegiete study with like-minded individuals.
Please stop perpetuating this as an argument on how best to express these concepts (which is too subjective for there to be a right answer) and reread my post above. The core idea of this entire thread is the utilization of the sorcerer class to support primal manifestations of magic that would be the precursors to the magic practiced by bards, wizards, warlocks, druids, etc.
To that end, my question to you is - why do you think the sorcerer doesn't work for this? Are there reasons other than their normal spell list? Because that's not really a reason for me. It's far easier to curate/modify a spell list than it is to reflavor an entire class.