Here's why:
* Nouns are words that name people, places, things, or ideas. Examples: cat, house, freedom, John.
* Interjections are words or phrases that express strong emotion. Examples: Wow! Ouch!
* Conjunctions connect words, phrases, or clauses. Examples: and, but, or, because.
* Prepositions show the relationship between a noun or pronoun and another word in the sentence. Examples: on, in, under, by.
Nouns are the foundation of sentences and are a distinct part of speech.