Yeah, inch-pitch. Looks low-miles, maybe even just shop-grime on a new chain? Some collector/restorer will probably pay decent money for it. Do you have a full bike's worth?
You can check for wear by measuring the full length, hanging from a nail at one end so gravity straightens it out. You don't need the length per se, but how far the last pin is past the nearest inch-mark. If all the pins fall exactly on inch-marks, then the chain is new or very low miles. A worn-out chain is something like 1/8" longer per foot, though you can still ride them like that.

For some reason that I don't understand, the cool trackies used to prefer block chain (ha ha the original block chain, before bitcoin!), and yours is not block chain. I see a couple block chains on ebay at the moment for $400 each! Personally I would rather have roller chain (like yours), and roller chain is the right stuff for any bike with inch pitch that's not a Match Sprint track bike. Prices not as crazy as for block chain.

Since I sold my '33 Excelsior, I have no bikes with inch pitch, so I'm not in the market. Check out The CABE, where there are more American heavyweight fans, though I'm sure we have a few here too.