Why don't we use at when we use home? For example:
I arrived home
vs.
I arrived at home
or
I am home
vs.
I am at home
Why don't we use at when we use home? For example:
I arrived home
vs.
I arrived at home
or
I am home
vs.
I am at home
You can use both, they both mean the same thing, literally.
In common usage they are used slightly differently.
If I have just arrived home, I would say "I am home".
Whereas if someone asked me where I was, I would say "I am at home".
Idiomatically you would not use the word arrive often as a native English speaker, you would instead say "I came home". There's a little discussion about this here.