Why do we ignore some letters in pronunciation

🤔When I was in school, I used to ask a lot of questions....!!😃
One Day I asked Ms. Doris, our English teacher:"
Why do we ignore some letters in pronunciation. eg the letter....'H'.......in Hour, Honest, Honor..... e.t.c.........???"

Ms. Doris: "We are not ignoring them; they are considered silent." ...!!
(I was even more confused.....😏🙅😱😵....??)

During the lunch break, MS. Doris gave me her packed lunch & asked me to heat it in the cafeteria.

I ate all the food and returned her an empty container....!!😏

Ms. Doris:---- "What happened, I told you to go and HEAT my food & you are returning me an empty container??"

Me: --- "Madam I thought 'H' was silent"