The old saying "Don't judge a book by its cover" is very appropriate in our lives today. It is very important not to judge a person because of what you assume they are like

You can't judge a book by its cover means that before you can judge something, you need to take a deeper, closer look at it.

You can't judge a book by its cover means that when you have only seen the surface of something, you cannot know what is on the inside.

The value of something is not always obvious from what we see on the surface, so we should save our judgments until we have more experience.

Don't judge this book by its cover
I just look different than you
We've all got our talents
They're not all the same
I wish they'd understand
If they'd look past this cover
my story'd begin
Maybe they'd understand