We don't understand the soul, we don't understand gods-will, we don't understand Qi, we don't understand Orgone energy etc.

As such, how can we build moral incentives around any of these things?

We must understand something about them, and what you seem to 'know' is that sentience is a thing (that exist), and it arises from the human mind - I don't think this is anymore proven than any of the other red-herring counterexample concepts I gave.

Or to summarise/TLDR - Sentience? It doesn't exist, it's a desperate attempt to maintain the human-centric concept of the soul, stripped of religious tones to appear more legitimate. If you disagree, prove otherwise.