prepositions - Why do people say "I am home" instead of "I am at home"?

Why do people say "I am home" in the meaning of "I am at home"?

Here is the person who say "I am home" he is human being and not object as home. In addition, why people don't say "I am university" or "I am supermarket" etc?

Answer

Home in this sentence is used as an adverb, or adverb of place to be more specific.

Home means at or to ​your ​house or the ​place where you ​live if used as an adverb. This is only true for home, not house.

Other places are not treated as adverbs, and hence are not used in this fashion. That's why you can't say, for example, I am bedroom. But when home is used as a noun, you can say: "I'm studying at home"

When is home a noun or an adverb?

Think about these verbs: go, run, cook, buy.

• Can you go in a direction? Yes. Ok, so you can home use an adverb of place here. = I go home.


• Can you run in a direction? Yes. Ok, so you can home use an adverb of place here. = I run home.



• Can you cook or buy in a direction? Not really. These verbs aren’t about movement or traveling. You can’t cook down/up/around, so you can’t cook home (adverb).
  But you can cook AT home (noun).

When home is used as a location (and not a direction), use a preposition if the verb needs one.
“I cook at home.” “I looked at a home.” “I bought a home.”

Source: English Current (first link)