It's a myth that you require to be "smart" to do a Ph.D. You just require few basic skills, a good supervisor and persistence. You are good to go! Here's a quote which is another version of what you said and you will realize it's exactly the same. If this person could do it(with wide spread fame) why not you?
It's not that I'm so smart, it's just that I stay with
problems longer. - Albert Einstein
You can't be serious when Dr.Einstein said he was not smart. He is pure genius. Absolutely no doubt. He was saying that just to make ordinary people feel good.
It's a myth that you require to be "smart" to do a Ph.D. You just require few basic skills, a good supervisor and persistence. You are good to go! Here's a quote which is another version of what you said and you will realize it's exactly the same. If this person could do it(with wide spread fame) why not you?