Here is the url to the underlying methodology. https://cdn.prod.website-files.com/63ba0d84fe573c7513595d6e/...

    The components are:
         Housing
         Healthcare
         Food
         Transportation
         Raising a Family
         Technology
         Clothing
         Basic Leisure 

     For a mix of eight different family types.  
         a single adult with no children (FT 1)
         a single adult with one, two or three children respectively (FT 2-4)
         two adults with no children (FT 5)
         two adults with one, two or three children respectively (FT 6-8)

Does it allow for roommates?

The report only show cost breakdown for the 8 family types. https://lisep.org/mql

The middle class is dead. It is almost impossible to buy a home and raise a family in your 20s now.

When was it ever possible there — for someone with brown or black skin?

A quick web search suggests roughly 25% of US Black householders in their 20s were homeowners during the late 20th Century, according to

https://equitablegrowth.org/wp-content/uploads/2020/07/Homeo...

With Black populations of 15M-30M in US during that period, that means 3M-7M counterexamples to the implication that was impossible to be an American homeowner in your 20s (or child living in a home) if “your skin was black or brown”. At least in the late 1900s.

Since you referred to America as “there”, I have to assume you don’t live in the US. You can do basic online research, though. Please present contrary evidence if you have it.

It was relatively easy to own homes in rural and semi rural America in the 1900s no matter who you were. The communities might have been segregated, but one of the most charming neighborhoods I discovered while biking on the East Coast was a small rural Black village hidden back off the main road. It was like going back in time 80 years. Slow-paced, modest, quiet…a real gem. Guessing they wouldn’t have wanted a White boy there, though.