Use of singular person pronouns

Question

Why can't I use the pronouns I and me interchangeably in a sentence?

For example:

I disagree with her.

Me disagree with her.

She disagrees with me. She disagrees with I.

Answer 1

I is a subject pronoun --> "I gave it to her."

Me is an object pronoun --> "she gave it to me."

Subject pronouns do the action (except in passive voice)

I hit him (active voice)

He was hit by me (passive voice)

those two sentences mean the same but note the order of the pronouns.

Object pronouns receive the action (except in passive voice)

I disagree with her. (active)

She disagrees with me.(passive)

again, those two sentences mean the same but note the order of the pronouns.