IPhone 6s system taking up too much storage?

I have an iPhone 6s. Had it about a year. Recently I ran out of storage, I checked my settings and it says the "system" is taking up most of it. I read some articles that said to update it to newest update, factory reset it(as a new phone), and I've done everything. Right after I factory reset it, I checked the storage and nothing changed with the system. Can anyone help? It's taking up 5.43 GB out of 16 GB. I really want to keep my current phone!

5.43 out of 16gb is perfectly normal for an iPhone. The 16GB iPhone 6S was a trap to force people to spend more money that Apple was widely criticized for. I warned countless friends that their 16GB iPhone purchase would be a huge problem despite the fact they thought they did not need more space.

Nothing you can do. You'll have to run everything out of the cloud. Except for the really important stuff you can download to your phone.

Check your Photos - the deleted photos can take up space. Before you do this, back them up on your computer or the cloud

Then Once your photos are safe, here's how to really delete the unwanted ones:

In Photos, click on the Albums icon at bottom right.
Then open the Recently Deleted album.
Then hit the Select option at top right.
Then hit the Delete All option at bottom left.
Then hit the Delete XXX Items option in red.
And with that, you have finally removed all those photos and videos that you thought were already deleted but have been lurking in the shadows taking up valuable space on your phone.