who decides??

i just had a moment. only for the second or third time in my career that i can remember...
i am sitting here watching my class having free time and listening to their ALL ENGLISH conversations. and i wonder "who decided that I could be in charge of the lives of these young, wonderful children?? when did i become "adult" enough for this to happen each and every day?? i love my job (inside the classroom)!! i'm going to miss these little rugrats next year! and then again, who decided i could teach grade 5?! i'm kinda scared.

i remember my first day of teaching ever. in wawa. in the room i went to kindergarten in. all FOUR of my students had arrived and everyone else was gone. it was just us. and i wondered...who decided i can do this? what is going on here???