You are not failing for benig honest, you are failing for being you and applying for that job.
I don't think you are suited to that kind of job.
I know you're not a programmer, but a programmer may get a similar result as you if applying for that job. The personality of a programmer isn't good for meeting and greeting customers, and you may have that kind of personality. It won't help you to lie about it.
You wouldn't get rejected from some kind of basic technician type job, on the basis of you not being a positive energetic smiling normie. (and being a positive energetic normie might even work against you in that kind of job!)
You are only 19. You should think a bit about A)what your IQ is and B)what jobs are suited to your kind of personality.
I saw a job advert a while back for forklift truck driver.. I didn't go for it but it sounded appealing! Your personality would not be a problem in that job.. Actually, it might be, but far less of a problem than it would be in a customer-facing job.