100 year homes are pretty common in older cities of the UK and in the countryside. New homes are similar in price in a lot of cases. They have advantages such as better insulation, less to go wrong (in theory) but also disadvantages such as lack of parking, garden and "character".
I was curious about this, but also a bit lazy, and the easiest figures to find were for the US. A carpenter in 1921 in Boston MA (which is upper-end of the range given, but not outlandish) earned $1/hour or $40/week. According to this[1], that's $17/hour or $680 a week. That's just over half of what they get paid now, at ~$30/hour.
As to:
> At that time labour was cheap
For the random example I picked, in the US, labour was about 50% the cost it is now.
0: https://fraser.stlouisfed.org/title/union-scale-wages-hours-...
1: https://www.usinflationcalculator.com/
2: https://www.indeed.com/career/carpenter/salaries/Boston--MA