The term "Senate" comes from the Latin word "senex" meaning "old man", and obviously the US inherited the term "Senate" from ancient Rome. This is a basic structure of society.
The issue is that this particular group of people older than 65 at this particular time in world history (which you happen to be living in) are Boomers who are probably the most child-like, foolish, and ignorant generation of people in world history, due to the circumstances of their upbringing (post-WW2, high technology, opulence, drug use, sexual revolution, peace in the developed world).
This isn't ageism, since normally old people do tend to have more wisdom and knowledge than young people.
There is something that really went wrong with the Boomer generation. The goal of every society is basically to survive their Boomer generation which many are not really seeming to manage.
Notice that Senate wasn't the only governing party in ancient Rome. Also "old" is relative. It meant "too old to serve in military", with Sulla's reforms the minimum age was 31 and even before that most influential senators were 40-50.
For emperors: out of 80 only 14 were over 65. 2 resigned/died at 66, 1 at 67, 2 ruled only few months, so really 9 out of 80. Rome is not the place to look for old rulers
Right you have to distinguish between the executive and legislative/judicial.
The executive being young and legislative/judicial being old was pretty typical across the ancient world.
Also people tended to not live as long in old age as they do now, we have lots of advanced medical interventions we can do to keep our old people alive and accumulating power and wealth.
Also Rome had a much healthier triangle-shaped demographic/population pyramid so they had more youngish people to draw on for elite qualities. They also had an active military culture so young people could actually prove themselves in leadership positions and make a name for themself. In the developed world in the current period that is not the case.
In general, insightful social commentary have this sort of quality i.e. "I'm with you on this but where you've taken this idea seems out there", like by definition, but it does require a level of humility.
I'm not necessarily declaring what I'm saying to be insightful but what you're describing is what a typical reaction to insightful social commentary looks like.
The issue is that this particular group of people older than 65 at this particular time in world history (which you happen to be living in) are Boomers who are probably the most child-like, foolish, and ignorant generation of people in world history, due to the circumstances of their upbringing (post-WW2, high technology, opulence, drug use, sexual revolution, peace in the developed world).
This isn't ageism, since normally old people do tend to have more wisdom and knowledge than young people.
There is something that really went wrong with the Boomer generation. The goal of every society is basically to survive their Boomer generation which many are not really seeming to manage.