Who cares if an idea is totally original? The important thing is that it adds to he quality of one
's existence, to one's ability to live a productive and meaningful I\life.

I have one that I thought of in the early 80',s,still hasn't been done, but I don't have the money to do it .

My feeling is that there are always new thoughts and ideas, but they grow from previous ones. Just like life on the planet: one thing enables the next step in the process.

It seems to me that there are new thoughts/ideas relatively often. We have come from the stone age to the space age and without new thought this could not happen. Possibly it happens in layers that bring ideas into cohesion because of how we share information in different parts of our mind. People tend to have boxes that we compartmentalize our thoughts in, and when we receive outside influences that can shake up our status quo, then the way we organize those thoughts and that information can change which can bring in new ways of viewing things. So yes new thoughts/ideas can occur.

Most philosophical ideas have been pondered down through the ages, but each person has to ponder them all over again in order to bring them into their psyches and have them resonate.

New ideas are continually popping up also.

Not likely, given the ever changing environment in which we live and the constant flood of technological breakthroughs. How many people do you think ponder how to get their Smart Phone to download pictures faster or an even better cure for AID’s even 50 years ago?

Likely but impossible to test

A lot have been thought before yes, especially about the fundamentals, that is why things like classical philosophy still resonate today, but I do think that there are new things in the world, that were not there before. And even if that is not progress, it is still change, and with every new thing there will be new thoughts triggered in all of us.

I think over 6 million years humans, human brains, culture, society, the earth have changed so much that it doesn't really matter if my thoughts are original or not. My wildly intelligent and humorous thoughts are usually related to the situation which caused them to occur so they SEEM original. Your question is one I have pondered many times and finally quit beating myself up about it and just became comfortable with myself to accept what is - is.