Yeah man the standard soil test is pretty solid...
pH ( Just realized you already took a reading for this )
Organic Matter
Total Exchange Capacity
Sulfur
Phosphorous
Calcium
Magnesium
Potassium
Sodium
Boron
Iron
Manganese
Copper
Zinc
Aluminum
% Base Saturation Ca, Mg, K, Na
I'm sure the soil is full of plenty of microbial activity,especially an undisturbed non polluted area such as what you have there from what I can see..It is a living soil absolutely.. You can add some inoculants though such as compost & castings because as we know diversity is key when it comes to the soil food web..A lot of things you can do here but me personally I'd start with that test ( instead of a shot in the dark ) as soil can vary from area to area obviously,then you can adjust inputs based on the soil report to make it well suitable for a canna plant's needs..some aeration and all that good stuff.
Eyes on Fire could give you some valuable insight..I didn't @ Eyes because I now he's busy at the moment so I didn't want to put him on the spot but you could hit him up if you need to..Very knowledgeable
@hecno knows his stuff when it comes to using resources from the land.