It’s not at all time highs. Your chart combines the data for both genders, which causes the decline in employment to be masked by the separate trend of women working outside the home. Male prime age employment is down 10 percentage points from 1955: https://fred.stlouisfed.org/series/LRAC25MAUSM156S
A higher percentage of prime age adults are working outside the house than almost any time in recent US history. I don’t understand why an analysis of the state of US employment should exclude women, can you please expand on your reasoning?
The analysis has to compare apples to apples. Raising families and homemaking is also work. Women going to work outside the home reflects a change in the type of work, not the employment level. But your analysis artificially treats them as having been out of work before and now employed.
What America is full of is fake employment statistics that are artificially inflated by young people hiding out in school to avoid the bad job market.