Boomers have had longer to accumulate wealth than everybody else so today they should be able to more easily afford a house than anyone else today.

Houses, when boomers were younger, were on average smaller and less feature rich.
Inflation works the other way too. A large mortgage will become smaller over time in real dollars as a result of inflation (assuming you are paying more than interest).

In the past, most houses have been purchased by couples, usually with two incomes (I would say at least since some time in the 1970s this has been true anyway) and the oldest boomers wouldn't have started buying houses until the 1970s for the most part.

Most well paying jobs require training of some sort. Maybe college. Maybe trade school. Maybe something else. This has almost always been true. Nurse, doctor, dentist, electrician, plumber, engineer, veterinarian, mechanic, welder, pilot, lawyer, accountant, etc. are all typically reasonably well paying jobs. But they aren't the types of jobs you are going to get straight out of high school or with some meaningless liberal arts degree. You also can't afford a house right out of high school. Nobody has ever been able to. You have to have had a reasonably well paying job (of which many exist as listed above), saved money for a down payment, and increased your salary to the point where making a house payment is reasonable.

It seems to me that the biggest difference between Millennials and previous generations is having a plan. I knew what I wanted to do by the time I entered high school and I am doing it today. Generations post GenX (and perhaps GenX to some degree) don't seem to figure out what they want to do until well into adulthood...if ever. Casting about for just any job isn't likely to lead to success. It may sound trite but working smart is as important as working hard. Part of making that plan is figuring out what jobs are in demand, what jobs pay well, and working towards getting one of those jobs. Bonus points if something you like intersects with those items. I'm not sure what you consider an "average" job but working retail or food service or similar jobs aren't average, they are low end, minimum skill jobs with generally little upward mobility. My parents, who are boomers, both had what I consider average jobs by the time I was about 12. One worked for the county government and one worked in maintenance for the local community college. Together, they could afford a small three bedroom house but making ends meet was difficult. And many boomers did work two jobs and/or 80+ hour weeks for a time to be able to get to a point where they could afford a house if they were buying when they were young.

The older generation retiring is a small part of what creates jobs for younger workers. A growing population is a bigger factor. Every generation has been larger than the one before (well, except GenX but that generation is defined along a narrower range of years for some reason) and certainly by the time you are of working age, there are even less of the older generations around. As of 2020, around 30 million boomers had retired (and I'm sure millions are dead as well). Also, many boomers still have not reached retirement age. The youngest boomers won't be 65 until 2031. I doubt there are all that many Boomers working that don't have to...politicians aren't exactly a good representative group.