Welcome to the forum @shinybabykoi
Most of us are familiar with the frustration of getting a nomination rejected. Walking trails are definitely eligible, though you typically want some sort of physical anchor point for your nomination, like a trail marker, even if it’s a fairly simple marker. You can see a clarification on trail markers here:
I suspect the fact that you took a photo of the path is why your nomination got rejected, because it isn’t focusing on a physical anchor like a marker. If there are any markers or other physical objects that represent the trail, it would be best to take a photo of the marker/object and submit the trail that way.
You should be careful when looking at existing nominations in game, as sometimes things get incorrectly accepted, and other times they may be from a long time ago, when the criteria was different.
In this case I think the existing wayspot you’ve shown may actually need looking at by Niantic. Whilst the trail you’re trying to submit is marked on maps and seems to be a great place for exercise and exploration, the Pavona Walking Trail does not seem to be marked as such on any map that I’ve checked, and it seems to be just a very short footpath that doesn’t actually go anywhere. I suspect the submitter of Pavona Walking Trail may have been intending to mislead reviewers with that submission, though I will leave that judgment up to Niantic.