I'm not gonna say I'm an expert or a pro, but when I first started kickboxing I felt the same way you are, if you stay consistent you will realise that there are no winners or losers in the gym, everyone has the same goal, to be a better athlete.

What I've also noticed about the guys who are not the strongest or physically imposing is that they focus more on technical ability, so what you lack in physicality you may very well compensate if you are dedicated to learning how to use proper technique.

And lastly, just have fun. I heard this saying that "in order to be the best at something, you need to be willing to suck at it at first!" With that being said, nobody is gonna judge you for not knowing what to do on the first day and as long as you are willing to learn and to fail, I think you will grow as a person and achieve your goals. I hope this helps