IPhone says I used up 3GB but how?

I bought an iPhone 4 from a guy. Everything works but I realize after downloading like 3 apps on MB it says I used 3GB! I realize the guy was logged in to iCloud so i deleted its data.
The search on the iPhone still pops up his iMessages but when i click the app there's no data. What is taking up my storage? I have no data that I know of that I used up other then the three apps.

IPhone says I used up 3GB but how

Added (1). Edit: ugh so long little bird ):
I do not want to jailbreak it but 3GB is alot of space taken up.

Would i lose flappy birds? It was on there when he gave it to me.

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