In practice, miners ensure the safety of the net by performing the PoW computations and then the nodes reach a consensus on which of the proofs of work has more "work" on it and thus the "mined" block is adopted as the valid one.

It is true that miners don´t mine bitcoins, instead they collect the block fees (a good reason why they don´t want to increase the block size) and receive some bitcoins for it, but the bitcoins are not created, they are already there since the genesis block.