Allah provides for us in ways we can’t see. He protects us in ways we can’t see. What our parents do for us, however, can be seen. We’ve physically experienced their love, mercy, and sacrifice.
If we can’t even be grateful to our parents for what we experienced in the seen world, how will we ever be grateful to Allah, Who does everything for us in the unseen world?
Being grateful to your parents is showing gratitude to Allah.