Ordinals is a scheme, not a protocol.

The usefulness of inscriptions is debatable but only because they are being recorded on Bitcoin’s timechain, not because of Ordinals.

Bitcoin provides the immutable chronological storage of transaction data.

Ordinals exist on the sideline playing a game that purports to track Bitcoin’s data, which it cannot.

Ordinals may interest you but there is no way it can be considered an open protocol akin to Bitcoin, Lightning, or even Nostr.