I'm a woman in 1st year of a mechanical engineering PhD in Europe. I've never been an excellent student in the past (before my PhD). I tried my chances in math and physics olympiads but I've never made it past the school level. In high school, I was in a class with genius national olympiad winners. They could solve the extra homework problems which I couldn't, even after few days. Our math and physics teachers prepared them for the competitions, but whenever I communicated that I'd also like to try they didn't take me seriously. I always thought they don't see the potential in me because sometimes the homework was quite hard for me.
For a long time I thought only those genius kids could do a PhD. But during my master's I got really interested in doing research (or just in being curious about things and then poking those things to satisfy my curiosity) and those interests got me into a good research internship which later got me into the current PhD program thanks to some good recommendation letters. Now I'm in a group with two other PhDs and they both have a long history of academic successes. They seem genius to me. They have knowledge of math which I lack and I have to spend time, a day, sometimes a few days, to understand our supervisor.
Will I be able to stay in academia for the whole career or will I hit a glass ceiling that only a genius could break? If there's a chance for me, what can I do to start to see myself as equals with those PhD students who used to win olympiads in school?
Update:
I suspected that I will hear a lot about impostor syndrome, somehow it's a trend on this SE ;) And I might have one, I don't know; FWIW, I feel good in my PhD, I don't feel that I "tricked" anyone into being admitted to the program. I know I did well in my research internship and that's why I'm here. My supervisor also tells me that she's happy with my progress, so I'm confident that I can complete this PhD.
In my question I wanted to emphasize whether there's a point in an academic career where you really reach a glass ceiling if you're not a genius. I was wondering if as a postdoc or as a professor you really can't go much further if you don't have that olympiad-level cleverness. I now learned from all the great answers that's not the case, which is very reassuring! Thank you all.