Let me offer you a simple proof. I want you to write two lists of items. The whole exercise takes 5 minutes: 4 minutes to write the lists and 1 minute’s reflection at the end.
Take a sheet of A4 or a new doc file on screen and set out two columns with two headings: List 1 - Failed, List 2 - Succeeded.
Instructions: start the clock and write down as many things you’ve had a go at as you can think of, irrespective of how old you were at the time. Anything that you totally failed at or gave up without completing goes into ‘List 1’. Those that you completed successfully or that resulted in a new skill go into ‘List 2’.
Over the last 25 years I’ve gone through this exercise with over six hundred people, but I can count on the fingers of one hand the number of people whose 'Failed' list was longer than their 'Succeeded' list.
Not definitive proof, but a jolly good indicator that the vast majority of us are far more capable than we think we are.