Why does “get” have so many meanings?

Because it’s an old and flexible word. Over time, people started using it in more and more situations. Instead of creating new words, English speakers just stretched "get" to fit new meanings.

Here are the three main ideas behind most meanings of “get”:

1. To receive or obtain

2. To become

3. To move or cause movement.

Example sentences:

I got a gift.→ I received a gift.

Get a job! → Obtain a job.

It’s getting cold. → It is becoming cold.

He got angry. → He became angry.

Get out! → Move out!

I got home at 7. → I arrived home.

Can you get the book for me? → Bring it here (make it move to me).

Then we add prepositions or phrases, and suddenly "get" takes on new meanings:

Get over → recover from (emotionally or physically)

Get along → have a good relationship

Get through → succeed or survive something difficult

Get by → survive with just enough