Emma,
You are charged to educate and the students are charged to learn.
What you do can enhance their learning or diminish it.
Attention spans, reading skills, medical and psychological issues, and parental involvement in their children's education, and well as the kid's responsibilities away from school, their communication skills, study support availability (such as but not limited to tutoring, technology access, counseling, advising, safe enivironments), the desire to learn, curiosity, and getting enough food and sleep are some of the variables that impact learning.
You just do your part and try NOT to be their friends. Be friendly though. There are substantial differences between the two. You are an adult role model.
You have an important task with this job. You can be successful and it requires substantial efforts to do so. You may not succeed with each learner. But you want each to be successful.
Do your best. You yourself can learn too for the betterment of your skills.
I wish you much success Emma. Your job is not an easy one.
I have heard all of this from the best of teachers I know. It makes sense to me.
Chrissy