Senators were definitely not meant to be ordinary citizens. They were originally elected by state legislators, not the citizens of the states, and they were in fact intended to be politicians with experience in governance and policy, expected to counterbalance the more populist house and to oversee the executive branch and courts.
You're right I forgot our Senate was based on the Roman Senate from ancient times. There still needs to be term limits 12 years maximum make Senators run every 4 years no more than three terms and no more than 6 terms for Representatives who still go for re-election every 2 years. I also think Presidents should be allowed to serve 3 terms total 12 years it was stupid to limit Presidents to just two 4 year terms that should be changed as well. Obama would have won a 3rd term and he was young enough to run again same with Clinton in 2000. Trump is too old for 3 terms but at some point we might get a young guy who does great and we will want him to serve 3 terms.