Looking at your comments I realized that some people don’t know you can stoke campfires with wood, to make them bigger and stop them from fizzling out.
Any combustible material will do, although the poorer it is (like leaves or grass) the more you have to put in.
Here’s how various size campfires look like:
All the way from tiny to quite large – there are 15 sizes of campfire.
During dry weather campfire reduces by one step every 20 seconds. When rain or snow is falling on a it, it reduces every 5 seconds. Therefore a fully stoked campfire will last about 5 minutes when dry, and only slightly over a minute when it’s raining.
The default campfire you place down is at level 3, that is you have about 40 seconds to stoke it before it turns into ashes.
To stoke a campfire you can either throw wood at it, or tap on it while holding wood. Either method works. Just don’t throw bombs or gunpowder kegs in :-)