The Raptors are reusable (even air-ignitable, with centisecond timing precision to achieve a specific thrust) engines with an oxygen-rich preburner, and to boot they have the highest chamber pressure of any rocket engine ever. Thus, they also have a very high (possibly highest, we don't know) pump pressure (the preburner _is_ the pump), and they're doing that with oxygen-rich combustion.
There is some crazy material making up that preburner chamber, and the pipes down to the pintles. Materials that until recently were though to be beyond manufacturing capability. And this is in a reusable engine that costs less than an RD-68. Frankly, it looks like magic.
> They might be called superalloys, but there is nothing particularly sophisticated about them
Inconel is known in the US as it was invented there in the 1930s - well before Musk was born. They might be called superalloys, but there is nothing particularly sophisticated about them from a scientific perspective. SX300 / SX500 are minor revisions which take some R&D but technologically it is 1930's stuff.