Bazzab, if your supervisor(s) didnt think you were good enough, they wouldn't have given you such an opportunity.
It's now up to you to work hard and not let them think they had bad judgement. It sounds like you have what it takes, don't ever give up.
It's totally "normal" to have doubts, we all do. I'm not sure WHAT kind of pedestal a certain "pretend-scientist" thinks he is on but he WILL fall off it one day. It's fate.