What changed
Ouroboros: the paper is the slots. The network is later.
The design divides time into slots and samples leaders from a stake snapshot. A live chain adds clients, parameters, delegation and an exit. Those are not the proof.
Original thesis
Stake, measured at a snapshot, elects slot leaders. The security argument is about that election, not about a yield.
What changed
Delegation let holders assign stake without running a node. Liquid-staking receipts, where they exist, add a second asset. A published rate is not part of the Ouroboros claim.
What remains useful
Read the paper for the stake and slot mechanism. Read a current client and a current parameter page for the network. Do not collapse them.