It will vary depending on where you live, but the blueprints for our 1915 California house specified cement tile in the kitchen, which was on top of a Douglas fir subfloor. By the 40s, linoleum would have been more common, though there could have been some sort of underlayment put down too. Hardwood in the kitchen would have been unusual, but soft wood is a possibility in some areas, and depending on the condition and quality of the wood, you might be able to refinish that to use as flooring. (It's common to do that where I live, though it will not take dings and wear as well as other flooring options.) You may also want to test the layers further down for asbestos before removing the flooring, just to be safe.

ETA: Also, if there is access from underneath, you may be able to tell from there what the subfloor is made of.

I’m in Georgia and kitchens if this era were always pine t&g then immediately cover in linoleum

The green patterned is sheet vinyl. The speckled terrazzo looking stuff is most likely to be asphalt tile/vinyl asbestos tile -- the particulate appearance doesn't really look like linoleum.

Patterned linoleum was more marble-y or streaky with more distinct patterns :

Maybe have it assessed for asbestos before you proceed any further.

ON A SIDE NOTE: That was the linoleum in the house I grew up in! Was called Marmoleum...I think by Armstrong. No wax flooring. LOL.