People were slightly smaller in the '40s, but the main difference is that they had a lot less stuff. Compared to the purchasing power, furniture was more expensive and a vast majority of today's appliances did not exist at all.

A typical kitchen had a stove and either an old-fashioned icebox or a fridge, and that was it.

I noticed some toilets in older houses in the bay area were comically small for me at 6'2" and I as I rule couldn't see my face in mirrors standing up (they were mounted so the tops were about at shoulder level. People from different places around the world are also different sizes (a lot of this has to do with multi-generational semi-inherited nutrition availability)